I just changed from a 383 to a 408 (400+.040) because the 383 can have issues if not done carefully. Some builders take a 400 crank and turn the journals down to size of 350 to fit block, which,when you think of it,why not just run it in a 400 block w/proper size journals and build from that? 400's really only have overheating issues if not maintained properly.They're not like a 350 where you can run around for weeks with a bad radiator in stop-n-go traffic with the ac on in 95* weather.If you get a 400 too overheated they can fail, but if you just spent big bucks building it up wouldn't you be sure to have a good hi-flow waterpump,180* t-stat,and properly sized fan and radiator? Don't get me wrong-I loved my 383 but I love the idea of the extra cubes and know it (the 408) will stay plenty cool if I take the proper care and precautions. A 383 can be built in more than one way, so be cautious of "cheap" setups. From everything I've read,rod geometry and torsional stresses can be, but not always are, an issue-depending of course on the quality of the build and method used. Do alot of research and homework before you make a final decision, then you know you'll be comfortable with it. I've had the 383, but now I've Graduated to the 406/408 platform-so you know which vote I cast.