you could try the ae86, im not sure how well it'd fit or anything but it's probably worth a try if you can get one for cheap. i like your idea about guages below the radio, i can't believe i never thought of that, its nice a low key but in good sight to. i got a tach mounted on my a pillar, but it's not one of the huge 5" monster tachs with shift lights and ish, but its still kind of heat though. to be honest i'm not sure how much the TOMs ecu cost, i seem to recall somebody saying they paid between 500-1000 for it, but i don't know if thats with a core exchange or what? i guess you'd have to contact TOMs, or you could try around twincam.
i got my silvertop w/ tranny, ecu, full harness+cut harness, toyota timing belt and thermo in the boxes for 700$ (Canadian), seemed like a good deal and he was a 15 minute drive from my place. probably spent 100$ +/- at the wreckers for random parts and the auto->5spd conversion. 100$ for a gas tank and fuel pump, 100$ for ae92 disk brakes (not needed directly for the swap though, just a good idea), 100$ on stuff like header wrap, k&n cone, belts, etc. i'm doing everything myself, so that saves alot of money. only labour im not doing is the wiring, i dont know enough about the wiring to do this, so im paying somebody with the experience in the swap to do it for me. after that i'm having a new exhaust system bent up, and i still got to run new brake and fuel lines (i'm running ae92 gt-s disk brakes at the back). probably 2000$ +/- for the swap. spend another 1000-2000$ on some rims and tires, little suspension, brakes, etc. the money i'm investing, i'm investing into transferable parts mostly (engine, brakes, rims/tires, etc.), my ae82's body has seen better days, so besides fixing the rust and priming it, thats all its getting in the looks department. in a year or 2, when i got a better job (im going to school for auto tech.) im just going to part out my 82, into a ae92 or ae101 and really build it up.
as for whiteline, i remember seeing they had certain parts listed for twincam, and non-twincam versions. you could email them and ask about it, they were really helpful when i talked to them.