312 to replace existing 302

[Awca12a]

My '57 Wagon had it's 312 replaced with a 302 that was dressed as a Thunderbird. 
It works fine but it isn't correct and I'd like to put together a powerful engine (within reason) as part of the restoration.

The people at S&J Engines will sell me a re-manufactured engine less all the accessories, etc that I'll have to find somewhere.
https://www.sandjengines.com/rebuilt-engines/Search/FOR-312LB
Since I'm not mechanically inclined, its good that they will have done the hard part and that I can read and follow directions fairly well.
They are willing to insert whatever CAM I come-up with so with some research, I can get more than stock torque out of this.

Just how difficult will it be to put this together assuming I know a travelling mechanic who can help mate the engine to the flywheel when the time comes?
Got the engine hoist, stand, room and probably most of the tools and I'm in no hurry as the car has an engine already.

I know it would be easier to hire someone but that just misses the whole reason for doing this.

Any suggestions would be welcome.

[hiball3985]

Keep in mind nothing from the 302 will work with the 312, starting with the flywheel and bellhousing and starter. You didn't state what transmission you are going to use. Also the motor mounts, what did they use to install the 302 and can the stock mounts for the 312 still be used on the cross member.

[Awca12a]

For future readers of this post, found out that the only intelligent way to do this is by getting a donor vehicle which will have all the brackets and mounting reference points necessary.  The heads can always be milled and pistons replaced but it's better to go backwards with an existing but probably non functioning setup than forwards with an engine but no receiving hardware.

[Frankenstein57]

Over on the ford barn, for sale , a guy has a complete 312 with all the brackets and accessories, with bell housing and trans for $700, in Boston.   Mark