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Ok, I am having second thoughts about modifying my MKIIs. I really wish I could listen to the original design at this point, except ones that I got are missing loads of parts. I know I can replenish those parts to get something going with the original driver boards, but I don't feel like doing things in instalments. I would rather decide on a system and work on those MKIIs as one project.
So, for those of you that have listen to the original and different updates, what are your impressions? CTech, who is offering MKIII restrorations on eBay, seems to think that MKs sound their best when left as they are with 6AN8s and mods are waste of amps and money. http://cgi.ebay.com/Dynaco-MK-III-Mark-III-MK-III-Complete-Restoration_W0QQitemZ280114451929QQihZ018QQcategoryZ50593QQrdZ1QQssPageNameZWD1VQQcmdZViewItem
A bit extreme, to say the least, but everyone's entitled to their own opinions and I would appreciate yours! Thanks!

P.S. If I did decide on the original design, I would replace the phenolic board and get new parts anyway.

From what I've read, the pentode front end in the Mark II/III with the cathodyne splitter is serviceable, but not optimal. If I were in your position, and could get the old circuit running with a minimum of parts replacement (maybe coupling caps, selenium diode) then I'd stick with the stock design. If it took any more work than that, I wouldn't bother with the original circuit. I'd go with Shannon's board, or maybe the Mark III board sold at Triode.

This doesn't address the Mark II directly, but the circuit philosophy is the same:
http://www.diytube.com/phpBB2/viewtopic ... 66&start=1

Here's another thread where the question was asked: Why no more front-end pentodes?
http://www.diytube.com/phpBB2/viewtopic.php?t=750

I'm sure there's more threads discussing the pros and cons of each if you search long enough. That said, some people like the sound of the pentode front. If you happen to like it, go ahead and listen to it. Unfortunately, the only way to find out is to build it...

Well, some people attest that the sound of
stock MKII driver board is a bit sterile and
lifeless. If you have a functional stock board,
ie. one that has not yet decomposed, why
not try it, first. It would be best to entirely
re-cap this board before applying power.

The first thing you need to do is refurbish
the power supply. If those units still have
selenium diodes, replace them with
suitable 'IN', 'UF', or hexfred diodes.
You also need to replace the filter caps.

The sockets for the rectifier and the
output tubes should also be replaced.

You may want to re-finish the chassis
as well. I did not do so with my st70,
and now I regret it.

Cool. I actually do have the original boards that appear to be functional, at least according the seller. I think I would give them a shot. Who knows I may end up liking it. If the sound quality is anywhere close to my ST-70 with a diy board, I'd be down with that.
The chasses + iron bells came completely refurbished. The guy spent $125 to get them professionally powder coated in metallic bluish green. The bells were re-chromed. It will probably look good when they are complete.
I have one more question. On the original board, there are 12 MMF, 390 MMF, and 750 MMF capacitors. What are these units? It is like milli-micro Farad? Maybe, 10^-3 x 10^-6 = 10^-9 or nano Farad??? Thanks.

On the original board, there are 12 MMF, 390 MMF, and 750 MMF capacitors. What are these units? It is like milli-micro Farad?

To us old timers MMF is Micro-micro farads AKA PF or pico farads now.
Use siver mica caps for those units.

MMF = PF (pico farads)

Here is a conversion sheet:

http://www.justradios.com/uFnFpF.html