bbk and pp make good throttle body's, or atleast they did. now as for what size has to deal greatly with what your plans are for the engine. there's 68mm, 70mm, 75mm, 80mm, 85mm, 90mm. the size tb you get will be very dependent on the air flow demand of the engine. to big is a waste and to small will hold your engine back. work up an idea of what you want to do with the engine and then resubmit this question with a layout of all of the mods intended and with the vastly experienced people on this forum i am confident you will get a very accurate reply.