differences between 273 crank and 318 crank?
 

what are the differences between a 273 crank and a 318 crank out of a 1988 d100. I know the 273 is forged and the 318 is cast but is that the only difference. im doing the "parts book for a 400hp 318" build but have a automatic and the converter won't go on the 273 crank what can i do and still achieve 400hp. can i use my 318 crank is this a stength issue?