Jesel or Westcott can supply any kind of cam core you'd need. If 900hp on most dynos with a N/A 400" R5/P7 is the goal, it wouldn't be difficult and could be done on somewhat of a budget. Getting 1100hp+ with a N/A 400" R5/P7 will get spendy, no different than doing the same thing with a SBC. A current new competitive Comp Elim. small block fetches 100k-125k, depending on who you write the check to.