Turbo'ing my 3SGE, rebuilding engine for it.

Have you considered a 2gr?
 

Your direct questions - boost will vary on your build / injectors / other factors and will be decided on a dyno tune. You can run 3sgte or 3sge or aftermarket camshafts, this will vary where and how much hp you make.

Speak with wtf auto as to local advice/specialist.

Depends on your driving / performance requirements. Mr2 is a personal choice. Options options

3sgte build. Requires so many components and costs not listed, clutch, dyno time - too many to list before even the nice to have like e153 gearbox etc. I have reservations at your cost vs outcome. You would be best finding a smashed mr2 turbo to put everything across, or caldina (gen4 swap, injectors, ecu, plug and play almost).

Realistically if you want 3sgte sell your mr2 and buy a turbo car for your turbo fun, there are many differences in brake components, options. Turbo cars are for sale, freight to wa from east coast around $1500.

2gr - 2grfe - $12-$15k for amazing drivability and low rpm power (will out perform 3s build spec). Use your car for the transplant. If you destroy the engine they are cheap off the shelf.

K20 swap. K20a engine / donour car with ecu etc, conversion kit from Hux Racing. Little more voodoo to K20a swap. If you destroy the engine they are cheap off the shelf.

5sgte. 5sfe block, 3s head. Stroker pistons, head gasket, aftermarket ecu etc is similar costs to your proposed 3sgte build path / costs. 5s blocks can be found for a couple hundred and is about the only additional to your 3s build path. More drivability, more potential. This will likely be more expensive than options above, depending on build spec, however potential depending on turbo selection.

Budget $10-$15k for whichever way you go in engine swap where that you can drive it with confidence (service items done). You can do it cheaper and often you will need to spend more.

2gr/2grfe = v6 meaning great torque (feels fast and can tow a boat) and 300rwhp.
Kswap will produce (hp) for what you spend from n/a 200hp to turbo at 800rwhp. Great option that will be cheaper than a 2gr, but you can build on it over the years to have more performance/hp than 2gr. There is no “cheap” big hp reliable solution, it costs to play.
Caldina provides modern technology, simple bolt ons and will see 300rwhp with the fun of turbo.
My personal choice is 5sgte, staying with a Toyota engine, ease of build, ability for gentle performance in low rpm and then boosted performance in mid - high rpm, flexibility in hp (how fast it works) by changing a couple of components that will yield 250-600rwhp.

Or sell yours and buy something where it has the engine you prefer.

Get to some club meets to see other cars with what you are thinking, get to wtf to talk through what you are thinking and what their advice is (and local costs).

Dont like k-swaps, thinking of substituting my 5sgte with a k24 😁