Welcome to the Team Brad!
Why stop at the four inch thirty over (4.030") bore of the 383 when you can start with the four and an eighth inch bore of the small block Chevy 400. Punch it another thirty over and you get the popular 406. Punch it sixty over with an aftermarket block and you are looking at 409 decals and emblems as it displaces a little over 408 cubes. (I of course would stick 283 decals back on the engine and retain the stock air cleaner with a Holley four barrel under it).
An aluminum Edelbrock RPM Performer intake (not the Air Gap, but the stock looking dual plane intake) painted orange could slide buy. Especially with the intake bored to accept the oil fill tube and retaining the stock valve covers sitting on top of some 195 cc AFR Eliminator fully CNC'd heads, also painted orange. The heads on top of an engine determines the amount of power you can make; so as a general rule half the price of the motor should be in the heads.
Any 200R4 you find will need to be rebuilt with aftermarket hardened or billet steel parts to bring it up to spec in terms of resisting the force of a big block. At over 400 cubes it is as big and powerful as a big block just two hundred pounds lighter. Input shafts and sun shells in stock condition will not survive the torque a 383 or a 406 can generate. The 700R4 isn't any stronger as far as that goes, just cheaper to buy and rebuild, because there were about seventy 700R4's built for every 200R4 made (excluding the 4L60, 4L60e, and 4L65e variants).