This will require a stroker kit and be very expensive, and I believe there is a problem with finding the proper pistons, but, if you take a set of 400 Chevy pistons (4.125 bore, same as 361), and with the proper altered piston pin (bushing the rods for the 361/383, then recalculate the new stroke, I believe there would be an application of a very expensive crankshaft custom made for this application. There is one other way to make a 400 cubic inch engine, and that is to use a 413 or 440 crankshaft cut down to your journal size, then have the proper height pistons added from the 400 Chevy collection, or any custom 4.125 piston after you calculate the piston height needed.
There is no way to get 502 out of any calculation, the largest crankshaft you can put in a 361/383 is 4.15 inch stroke, which requires a lot of external oil plumbing, internal shaving of casting, and you come up with 443 cubic inches. In my opinion, for the cost of doing this, and the trouble to go through to make the necessary alterations, put a blower or turbocharger on it and have one heck of a strong 361 B block engine. The difficult part is cost of the parts to make it work.
There is no way to get 502 out of any calculation, the largest crankshaft you can put in a 361/383 is 4.15 inch stroke, which requires a lot of external oil plumbing, internal shaving of casting, and you come up with 443 cubic inches. In my opinion, for the cost of doing this, and the trouble to go through to make the necessary alterations, put a blower or turbocharger on it and have one heck of a strong 361 B block engine. The difficult part is cost of the parts to make it work.
