Hello,
The 2000S IMHO IS THE FINEST BASS AMP OF ALL TIME. Mister you are undertaking a large task in building a 2000S from "scratch". Good Luck sourcing the parts. Here's a suggestion and DO NOT BE OFFENDED, Buy a 1973 first GENERATION MODEL T. No "mid" switch. It nails the 2000S sound. Plus it's 24" wide and sits nicely on all 3 of my Sunn 200S and 215S cabs, all with JBL K-140's of course! Take it easy and again good luck. i LOVE MY "t". Some Model T's on EvilBay and Craigslist. going rate 'bout $1200 YANKEE dollars. We are "rooting" for ya!
PEACE SUNN LOVERS