OK, taking another look at my 3630, there's clearly been a design change or two since the original mod article was written. It talks about 3 LF347s - mine only has one, and a pair of TL084s (which I'd already swapped for TL074s). Mine also already has THAT 2252s instead of DBX 2252s (guess the stock finally ran out) , and THAT 2150As instead of DBX 2150s.
If your 3630 schematic talks about TL084s (not 81s, my mistake) then I'm guessing it was updated too - maybe there's half a dozen different variants out there...
If I put a pair of THAT 2180s in there, I'm guessing I don't need/want the trimming circuit (R7, R66 & friends) going to pin 4 - the 2180 datasheet says to leave pin 4 open circuit.
BTW if you still want a pair of THAT 2552s I can send you a pair for $15 plus postage.
Jon.