ive been doing alot of research since one of my mates told me to use a RB25neo as they got good flow i found .lewis engines can port a RB25 neo head 308CFM for $2000 and there RB26 headFully ported is 300CFM with bigger valves for $9000
http://www.lewisengines.com.au/category15_1.htm
they need to make more cams support for the RB25neo
cheers