Dynaco ST 70 - Best mod value?

After reading Peter Breuninger's, "The Classics," in Listener (Sept/Oct 2001), re: the Dynaco ST 70, my interest was piqued and so I therefore went out and picked myself up a nicely maintained unit. Initial impressions, haphazardly setup with some old gear hanging around in my basement...CJ pre, Tannoy Royal Blue Monitors, first generation Rotel CD player, confirm this amp as the bargain-basement audio gem perhaps of all time. At any rate, I've now got the bug to take it up a notch, choosing from among the multitude of mod option/package offerings. I am wondering whether any of you have had any experience in this regard? Among the choices I am aware of/considering are the Welborne/Alan Kimmel mod, Van Alstine, Curcio, Triode Electronics. I welcome your comments/advice.
The easiest up grade is put in premium EL-34 's. I have found the best results with Groove tube GT-E34 LS tubes.

Don Kenney
I have owned most of the mods, but probably the best and most consistent(IMHO) was the Audio Research, as described in Audio Amatuer and I know there are one or two companies out there that sell the kits or do the mod, may even be Welbourne Labs. I also liked Van Alstine's, but it was one of the older units and I am sure has changed. Would also maybe perhaps ever so slightly suggest buying one of the mods that are out there used, cause, stock Dyna's are just getting scarcer all the time, and I am almost to the point that I hate seeing them modded. I have seen used AR Mod ST70's go for 5 to 6 hundred, and I don't think you could get a stock 70 turned into one for that.