Jut FYI, when I put the 200R4 in my 78 Wagon, I found the stock T-handle shifter already had provisions for a 4th gear notch, with some slight adjustment with a small file I was able to engage it and use the stock shifter. With the stock TH350 the cable did not travel enough to let the shifter go into the last detent. I thought it was odd, but it worked out well for me.
Personally I had a Megashifter back in the 80's in a 67 Lemans, I never liked the issues I had with the reverse lockout sometimes not disengaging. Made it a PITA to use on a daily bassis,
78 Sunbird Safari Wagon, 3.8 N/A, 1978 Impala Wagon, 1971 Lemans Safari
77 Astre Formula, some day soon powered by a 215 Buick V-8
1973 4-speed Lemans Safari STOCK!!!!! 1967 Lemans Sprint 2D HT 4-speed
1971 Lemans Safari/GTO Clone, 1969 Firebird Sprint 301 ci OHC6, T-5, 4.10 12 bolt posi