46 chevy truck 454 is in the shop

The truck is in the shop. Needs head work. Worn valve guides. I have been looking at North Coast Performance and a set of oval port alu. heads to replace the stock heads(casting#336781) and match the Performer intake and 750 Edelbrock on the engine. Has anyone delt with the company before? I understand I will have to use long studs available from ARP due to casting thickness. What else do I need to consider when replacing rether than rebuilding heads? I can not give up any more room at the fire wall, so if they are taller they won't work. I know the intake and exhaust cc's will make a difference but do not know how that works. Also the current combustion chambers are 113cc's but don't know how close I need to match. Also they say the exhaust ports are raised. I am assuming this affects the manifold to the down pipe.This truck is for crusing only.This engine is supposed to be stock from a 1978 suburban. Will be checking the numbers to verify.