h22a/1 (obd1) is a direct drop in for a 4th gen prelude
imo it is one of the easiest to do
some b series are easier because you can lower the car onto the engine to simplify your life, whereas with the h22a you have to lower the engine in, unless you take the crossmembers off which is a pain

you will need:
h22a/1 engine
ecu

those are the basics

u can use your current tranny
u can use your current axles
u can use all your current mounts

usually the engine+tranny+ecu swap is the best thing to buy

u will also need to run 2 wires from the distributor area to the ecu area for VTEC, you can ground the 3rd VTEC wire to the valve cover or thermo housing if you wish, u will also have to modify the ecu harness to accept these 2 wires, or run the wires into the ecu somehow and solder them to the board.

might i recommend changing your clutch and timing/balancer belts before the engine goes in the car.

it is 100 times easier to do these things when the engine is off the car

good luck
~boomer