Rega RB3000

I have a Rega Planar 3 Turntable, and I have upgraded to the Apheta 2 Cartridge.  I am now considering upgrading the Tonearm to the RB3000.  Is this a complete waste of money due to limitations of the plinth or other aspects of my deck?   I don't really want to buy a whole new turntable right now.

I have already upgraded the sub platter with Groove Tracer's product as well as reference band to drive it.  

I have the Parasound JC Jr phono preamp and my amp is PrimaLuna Evo 400.

Thank you for your comments.  I have only been doing this a few years but love it.
If it fits, it can only be an improvement. But why not upgrade the table? You know that's what you gotta do.
I'd save until I could get one of Rega's better turntables.  I'd rather have a better plinth with the RB300 than the RB3000 with a lesser plinth.  Ask your dealer about this.
I think that for little extra you get the Planar6 which is a better proposition than putting RB3000 on a P3. Just my thought.
@ronin35 For a similar price take a look at the Audiomods arm - they are so much better than anything Rega has to offer at the same price and will fit the Rega turntable perfectly.

I have never regretted getting mine - a superb piece of extremely high quality engineering.

Mine has the one-piece harness and the micrometer VTA adjustment.

Also request the Absolute harmony RCA's - they are a perfect match

Here's my review of the ARM and the RCA's

If you have any questions just ask

Regards - Steve
Thank you for all the input.  I am leaning towards upgrading to the RP8, but  I have new speakers coming so I will wait until I listen with the new speakers before I upgrade.  With Covid isolation music has been my sanctuary.  I am, therefore, having fun with upgrades.