[olddog]

Take a look at how much room there is between the engine and the car, especially on the sides. Also use some silly putty roll up about an inch diameter at maybe 3" long and put them around the air cleaner. Close the hood. Open the hood, and the smashed putty will tell you how much clearance you have.

A 351 windsor is the same engine family as the 302/5.0. Off the top of my head it is about 3/4" taller and about 1-1/2" wider. The heads interchange. Front to back the block is the same length. If there is plenty of room, I would go with that block. If not, I would go with a 347 stroker. There will be almost no extra work to put the 347 in, and it will be a little less cost.

If it will easily fit and it fits you budget go with a stroked 351W. I don't think the 460 cid stroker version is worth the extra cost, but some do. I think the 408 stroker is fairly inexpensive in comparison. Built mild you should have more power than you need.

No one has discussed radical cams and difficulty to drive. Even worse, longevity and maintenance. The more power you make out of the same CID, the more radical you have to go in the build, NA. If you focus on peak Hp, you end up with steep torque curve. A high radical idle. An engine that wants to buck and hop at low rpm. Generally has poor street manors and is a fuel pig. It will have a short life and require a lot of maintenance.

Understand your tolerance to all of this. You can also get an engine that makes good power everywhere, that is reliable and has good street manors. It will not hit the High Peak Hp of the radical build, but it could easily have more power at cruising rpm. Note that in these cars, you do not need huge Hp numbers. They are fast enough to easily get you killed at modest power levels. Don't get caught up in chasing huge Hp numbers. The fact is that you can take the same engine and have it dynoed many places and get just about any number you want. It's not an exact science, even though it should be.