well when I had my 83 D250 with its 318, I put a set of EQ Magnum heads, a stock 360-2bbl cam and a Performer intake and carb on there along with some Hooker super comp headers and it made a HUGE difference. HUGE.
What was the ET with the stock 318 setup versus the 360 setup or the dyno results with the stock 318 versus the 360 setup, if you have them? I certainly don't mean to suggest your are being dishonest since "in the seat" observations are extremely subjective, but I'm highly incredulous that putting a smogger 360 2bbl cam that craps out at 4,800rpm, 360 Magnum heads, 360 Performer intake, and Hooker Super Comps on a stock 318 saw noticeable gains in a 1983 D250. While a head porters and others on here might have the actual flow and dyno numbers, 318 cubic inches and a cam that doesn't make power over 4,800rpm in no way will flow enough to keep up with the 360 head/intake runners and Super Comp headers. That combo would seem to kill a 318 far more than make "huge" gains.
A 318 with stock 318 heads, Edelbrock LD4B intake with factory 318 runners, around a 340 cam grind with power up to 5,800 rpm, 650(ish) cfm carb, and full-length (not Super Comp) 1-1/2 or 1-5/8" headers with 2-1/4" exhaust would smoke the setup you describe comparing apples to apples. Do some porting described in this thread to those 318 heads and you'll see even more gains.
