once, and had some decent results.

I put a set of truck (don't remember the castings) 305 heads on 1 383 with flat top (four eyebrow) pistons.

We ported and poslished the snot out of the heads.

This was in my 85 Franken Vette, back in 94 or so.

Results:

I went from 13.8 in the quarter to 13.01
Gas mileage went up by 4 mpg on the hwy and 2 mpg in town
My 60 foot went down .4 and my 1/8 mile really improved (that was my biggest gain), but I don't remember that number.

We went with 1.94/1.5 valves on a fairly mild crane 2040 compu cam and 1.5 full roller rockers, headers, and 3.07 rear gears on a 700R4 trans.

I drove the car with the 305 heads for three years. Sold it to a guy that drove it another year that way until he submarined the car on a flooded rod and bent a rod.

Long story short...it worked for me.

However, my fuel injection with the use of the knock sensor kept me safe, and I had to run premium gas all the time.