318 to 360 motor swap. 1974 Plymouth scamp
is it something I should have a shop do?
Nah, if you've got the space and tools to do it yourself I say go for it. When I was 18 I swapped my slant out for a 318 I built and it wasn't that hard. I had no prior engine swapping experience. 318 to 360 should be a piece of cake.
The 318 should have a 904 transmission behind it, which will work with the 360 but you will need a weighted flex plate since the 360 is balanced differently than the 318. Keeping the transmission would let you keep the driveshaft, saving ya quite a bit of cash. A 727 is nice BUT...it eats up more horsepower than a 904, and a 904 is still a durable enough transmission to handle the 360. All the wiring and stuff should transfer right over, and you can reuse your accessories. If you're good with wrenches and a hammer, you could have it swapped in a day :burnout:
Power steering shouldn't be an issue if you get the right headers, which are not necessary if you can give up some horsepower, but if you want headers now is the time. They SUCK to install with the engine in the car. I've been running Hooker Competition headers on my Dart and haven't had any issues with the power steering. If you decide to get headers, definitely get a mini starter too because if it ever goes out, you'll be glad it's a lot smaller than the original style starter. If you go with manifolds (which definitely are easier to work around, as KrazyKuda mentioned), disregard all of what I just said. You could always just use what the 318 currently has and upgrade later. Then you could keep your exhaust system, saving you even more time and money, for now. Since 318's and 360's have the same external dimensions (for the most part), everything should bolt on except the 360 specific parts.
At the very least you will need an oil pan, pickup, and a flex plate. I'm probably forgetting some odds and ends but those are the important bits. I'm not sure about the kickdown linkage and doing a 2bbl to 4 bbl conversion, (I assume the 318 is 2bbl and the 360 isnt)with an automatic transmission because my car is a stick, never had to deal with the auto.. Everything else is optional if you're willing to leave some power on the table or are willing to upgrade things down the road as the budget allows.
Just figure out what your goals are, come up with a plan, and stick to that plan. With good planning it'll be nothin' but a walk in the park! :glasses7: Good luck, and enjoy all that extra torque.