i'm new to stovebolt, and still trying to find my way around. my fire department has a partially restored '37 chevy/sanford fire apparatus. it has a 216cu motor that is bad. i would like to replace it with a 235 gmc, i think about a '41. are they interchangeable? also will the head from the 216 fit the 235? the head has been reworked for the ethanol gas. thanks