Do you think there is an advantage of the 80 mm over a 75 mm at the power level you are at?
I like this he351 over S480 combination, it daily drives great, spool-up is great, power is great.
I'd say the main advantage of the 80mm over the 75mm compressor wouldn't show up till 700+ HP and I'm not quite there yet with this truck.
I did tow Todd's Frankenstein truck up to the dyno event in Salt Lake last weekend and there are some nice long pulls on I-15 between Cedar City and there. We were using a heavy equipment trailer about 5,800 empty, Todd's truck is 7,200, my truck loaded with gear and 3 (large...heavy) men weighs roughly 8,000 lbs, so we were grossing 21,000 lbs.
With an EGT limit of 1250-1300, we were able to maintain the 80 mph speed limit up all of the passes. On flat ground it was no trouble maintaining speeds of 85-90 MPH although cruising boost was pretty high 25-28 psi and on the hills it hit 55-60 psi max when you really gave it some throttle on the hills....
If it was the middle of summer, we probably would have had to slow down and grab 3rd on the longest hills because coolant temps were rising with sustained 1250 egt levels and I think they would have become an issue on a 80+ degree day vs. 50 degree weather.
All that said, this was on the same tune-up that ran 12.6 in the 1/4 mile.
5x.016" injectors, 26* timing, 7mm delivery valves, no fuel plate but custom 65 psi afc spring, He351cw internally gated over S480 w/race cover 96/88/1.32 hotside.
If I added a small electric pump based water injection kit, I think it would run cool enough to maintain the speed limit on any interstate in the US grossing 21k+ even in the dog days of summer.