You don't Have to use the 91-93 setup. Fastback66 used a 79/80 setup. Had to cut the core support to clearance for stuff and the lower valance. I'd rather make the 70s grill work instead of using the 91-93 like everyone else seems to. Plus 91-93 is my least fave. Get a Rusty support to cut for mock up and a pattern. Could also try to modify the 91.5 to accept the early headlight buckets. Food for thought.