Not true at all, have you ever tried to put an SR into a corolla? It's no simple task.
With everything you listed that car prolly would make only 115hp on a REALLY good day.well its basicly bone stock all its got is a header n exhaust n a clutch when that 86 was my cuzins we sent the head n got it port polished n shaved n it ran hard enough to slide pretty easy but my cuzn loved to hear that thing bounce off the rev limiter it waz constantly abused n ended up blowin it. thats y im tellin him to throw sidedraft webers on it n get the head done that should make that car run pretty dam good.
If I was you Id stick to the original 4AG and put money into it. Toshiki Yoshioka stuck to original 4AG and won the D1GP. For this car in the drift world to be competitive you need response not horsepower to get the edge. Just look at Katsuhiro Ueo his AE86 compared to other pro drifters lacks HP but makes up for it in response and he's just as competitive in D1.
Just my 2 cents
Still original 4AG is the way to go.