The front drive snout on the blower is only long enough to reach the drive belt area---if you have 2 inches in front of the lower crank you have enough room---also if necessary you can run without a harmonic dampner because the blower drive belt will dampen the crank harmonics

Also the ford 302 is probably the smallest overall in cross sectional dimensions of all the v-8 engines and with the distributor being mounted at the front allows gobs more clearance at the firewall area

Your idea of the gmc 471 blown 302 engine is a wonderful choice not only for diminsions, weight , power/drivability, and visual appeal--------and its a ford in a ford!!!!!!!!!!!!