Re: 427 top oiler
The 427 block mounts in the mustang just like the 390. You can find parts for the 390 mustang at most of the mustang supply stores, such as Dallas mustang, California mustang, or Classic mustang in Oklahoma. You can also find used parts on ebay. 67, 68, and 69 parts all interchange for your engine. You might want to check on the clearance for your heads. You could have your heads drilled to fit the GT or CJ exhaust, then you wont have head fit issues.