Did a 79 a few years back, and did the usual things to make it fast. Changed the 7.5 out for a $100 8.8 with a $75 set of 4.10 gears. Did the basic truck motor with vortec heads and a cam. Got a set of free Hooser spring car front tires. Very soft and hooked great on the track. 12.20 et. and 109 mph. Hard to find those Mercs around here, was never a big seller.