I have had a fairly rare car. It is a 1968 GTCS, with all numbers pointing to a 390Gt. However I bought it with a 289. First and foremost I want to have a reliable car. Do I restore the 289 first, as I love driving it, then the interior and body. Or do I yank the 289 and put in the 390? It would also mean changing the trans as it is the one for the 289. I do want to eventually have a complete 390 car. But as $$$ dictate what is the recommendation?