318 to 360 swap
You can run it now on the 904. Just realize it's not a high rpm monster...lol. I'd just bolt it in. And truthfully, you can use some wahsers to make spacers and run the 318 steel bracket if budget says you had to. I did it for years on several cars... You will want the B&M flexplate for that 360 tho. Then it's a drop in swap. Also, if you use the 360 4bbl intake and carb, the kickdown may need some minor modification to get it properly setup. If you dont set it up right, the 904 wont last more than a few weeks tops. It's that important.