If you want to keep the trans look for a 390,410 or 428,its the same basic block as the 360 but has more power. The 410 is a big merc motor used in 1967 and 68 and is basicly a smaller bore 428,the 360 is tired in my 70 and I am thinking about going to a 302,351-w or a 300 six and AOD to try to get some gas mileage.