will a small block 350 bolt up in my 1983 cadillac eldorado?

 

Your vintage Eldorado received a large number of factory installed V8 engines from Cadillac 368 and 4.1 to Olds 5.7 gas and diesel. It also has the THM 400 transmission if I am not mistaken which is good. I would personally look for a Cadillac 425 V8 that should bolt in well, an Old 403 or 307 would work too and a 350 Chevy will be able to work as well. The 4.1 is a low output engine so I certainly understand your desire for more power.