Top vintage receivers vs. modern high-end equipment

I am considering pairing an old amplification system to my JBL Paragon -- the idea of getting an all vintage system is very attractive to me. Among other things, I am looking into classics such as the Pioneer 1980 receiver or the Marantz 2600. Does anyone have direct experience in comparing this kind of equipment (very high-end but 40 years ago) to current high-end equipment, imagine an integrated Pass Lab amplifier? How do they stack up? Thank you. 
I used to sell audio equipment in the stereo heyday of the mid-70's to early 80's. I found the upper end of Sansui receivers and the entire integrated amplifier range to be better sounding, more neutral and have greater detail than any of the other consumer brands that I sold. The G7000, G8000, G9000 and the holy grail G11000 (special order only) to be great sounding receivers with the best FM performance of any. My only complaint was the (to my eyes) garish "Tokyo by Night" styling and huge footprint. On the other hand, the AU 517, AU 717 (I bought one) and the hard to find AU 917 integrateds were very handsome (again to me) understated black boxes with amazing build quality and excellent sonics. I used my AU 717 to power JBL L-166's with great results. 

The later Sansui receivers and integrateds such as the x500's and x700's still sounded good, but the internals were getting cheap. Same with the "Z" series that followed, but they looked better. 

The one other brand of components to consider are the Technics separates from the era. These have been under the radar, but were well built, have understated styling and are neutral sounding. Look for models like the SE 9600 or SE 9060 preamp and SU 9070 or SU 9600 amps. I would still pair with a Sansui TU 517, TU 717 or TU 917 tuner.
Most of the guys I knew leaving Nam bought Sansui.  Seemed like it was good back then and I would suggest trying it.  This was late '60s early '70's.

The Marantz 7 mentioned above?  Just don't.  Even Saul told me it was not his best work, and that was in 1974.

I still have an Onkyo tuner from back then that works just fine.

NOT being rude, but with those speakers, I doubt it will make much difference what you do.  Sorry if that seems harsh.

When I retired I set about on a project to build a vintage system. I'm very nostalgic and looked for gear I had in the seventies. I have managed to compile a system that includes the same integrated amp, equalizer, and a model cassette player very close to what I had. I love it and it sounds amazing!
Yamaha CA 810 integrated amp
Yamaha CT 810 tuner
Yamaha Yp b-4 Turntable
Yamaha TC 510 cassette deck
Advent large speakers (4)
Luxman G-11 equalizer

I too sold hi-fi back in the 70's and 80's and I agree with rbstehno1 as far as his liking the Yamaha receivers and integrated from that era. Our store had a great repair shop that always had a few of the Japanese receivers of the day there for work. One of the things we used to do is set up the competition out in the listening room and compare to the Yamaha lineup. I won't rain on the lines that didn't cut it but I will say that the big name receivers of the day did not compare favorably with the Yamaha's for most part for sound and reliability.
I have one of those “inferior” 80 series Pioneer Receivers, a SX-1080. It sounds pretty damn good to me. every Pioneer fan I know does prefer the sound of the 50 series though. I have not heard one myself. I also know that 80 series Receivers do have some components that are near impossible to get but supposedly there are different parts that can be used if needed. 

I also have a Sansui 9090 (not the DB version), and that one I feel sounds better than the Pioneer. I had a Marantz 2275 which was ok, an a Yamaha CR-2020 which sounded very nice. I sold both of them as I’m trying to get cash for new Speakers.

i bought vintage gear because I wanted one system that had that older vintage sound. However, the other posters I agree with in the opinions that newer gear does sound better in many cases. None of those old systems sound as nice as my Parasound A21 and Goldenear Triton 5’s with two JL Subs, but I love each set up for different reasons.

In the end, get what sounds good to you, have fun with it whatever it ends up being and appreciate it for the history and sound that millions of folks like us loved and spent their hard earned money on back then. Happy Hunting!!