Thank you Mikes 66 The info on the 289 head porting will really help . And I will stay clear of the water jackets . I have full ported lots of SB Chevy heads in the past . But now I own a very clean 1965 Mustang 289 K 4speed car . I would like to build its 289 up to 350HP . And I think the only way is with a set of full ported 289 heads and the right camshaft .