Which is better?

4 speed all the way! better? I think so, cooler? definitely! weak? not on your life but if you are worried get an 18 splined 440, HEMI box, although the more common 23 splined ones are plenty strong, easy swap? NO WAY! there are a lot of obstacles to over come, and some of them aint cheap, brewers sells complete conversion kit's, (but you can find most of the parts cheaper in the FABO for sale section)

http://www.brewersperformance.com/products.asp?id=237