IMHO, I have a DOVE 429/460 in my car and these engines make 500 HP rather easily. IF the sleeving is done properly I don't see a problem. The biggest challenge with these engines is oiling. Since you are using alum heads, make sure you open up the return path for
oil drain back. These engines tend to gather
oil in the top end especially at high rpm. The other thing that would be good is for all bores to be standard clean up if possible. That way your sleeved cylinders will have a better chance of cooling properly.
Just my 2 cents worth.
eric