You aren't going to really be able to build a "clone" of an SVD. The SVD has a different gas system and uses a milled receiver, so right there you're stopped. Since you're not really building a "clone" but a one-off variation, or an accurized big AK, then the easy way is to just buy a Romak-3 and be done with it.
The VEPR is another great option. .308 chambering makes it attractive, and you can get MATCH .308 easy enough that would make a difference in performance over the surplus fodder most of us feed our Romak-3's.
Personally, my next project is a VEPR in .308. I intend to have the M14 mag conversion done (I already have a bunch of M14 mags for my M14s and M1A) and put a Choate T-hole in place of the wood. I'm going to use the wood version, as they are a tad cheaper, and I want the Drag type stock anyway, so a T-hole will work fine. I know that the RSA trigger will work in a VEPR, so I'm set there for a trigger.
A 7.62mm NATO AK with a great trigger that takes M14 mags? Yeah, that's pretty close to the perfect gun.
Ross