Speed costs money, how fast do you want to go?
I design machined components, so I'm familiar. I also help on the customer service end, so I have to be able to explain why things don't work the way some customers think they do, which sometimes helps me also explain stuff to folk not steeped in cutting fluid and cnc coolant.
360's fit into A bodies easier than a big block (383 is a big block). Big block vs small block is a matter of preference, goals, and what you already have. It's possible to buy a 'crate' (already built and done blueprinted engine) small block, but big-blocks need to be built these days. If I were to try and spend money on a big block, I'd want a 400 or a 440. I'd use a 383 if it was assembled and running, or I already had the entire engine and it only need honed and assembled.
There are multiple challenges with a big block in an A body. Spark plug access, header fitment, and engine clearance to the k member in some cases (I think). There's plenty of threads that detail the big-block swap process, but just know everything that attaches to a BB is different than a SB. Transmissions, exhaust, intakes, etc. Cost to build one is about the same if you already own the parts. Getting your hands on a big block is usually the challenge.