OK, so here's the scoop...
The Griz 704 is basically the same size table as the PM-25 with a head most similar to the PM-20. So, In other words, its a PM-20 with a bigger table or, if you like, a PM-20+ or a PM-25-.
BTW: Matt's machines are somewhat customized and he's improved most things that go wrong with them. PM uses different motors for example (same form factor but more reliable). The fitting and scraping are improved... Matt has been working to find a DC motor for those machines as all of them (his and the Griz units) would benefit greatly. FWIW, we see a lot of posts here about people looking for various replacement parts for the 704. Those threads come-up about every week or two...
As for converting to CNC... Anything is possible and there are aftermarket parts of all sorts. Search this and other forums and you'll see many folks who've been in the process of converting them to CNC for the last couple years -I often wonder if they actually make any parts with them. Indeed, I am admittedly imparting some of my own personal philosophies here but, these kinds of conversions are hobbies within themselves. -Nothing wrong with that! After several years (and significant cash burn) of working on older equipment, I have decidedly fallen into the camp that I like to work WITH my equipment and not ON my equipment. -Totally valid if folks want to go the other route or perhaps somewhere in-between... It's a free world.
Although it might be more $ than you're considering right now, the PM-45 is now CNC converted at the factory. You can buy a version of the PM-45 for less money that has all the factory mods to later upgrade to the full (or partial) CNC version. It's not on Matt's web site because he didn't think people were going to go this route but, it just so happens, he has a couple in stock.
Hope that helps...
Ray
Ken,
Just like with lathes, most all these machines are pattern copies. Just the same way about 100 companies sell 1911 semi-auto pistols, many companies sell patter copies of shop equipment. Sometimes, a given importer will want certain features or possibly lower quality components to help them manage their profit margins.
I can help you find-out which PM is closest to the Grizz.
Ray