Swapping Newer Oe Lexus Parts To Older Lexus (Ob1-Ob2)

[Portugee420]

So here's the story... I let my little bro borrow my SC400 while i dropped an engine in a sweet mpg saver i picked up for his graduation (95tercel) pics soon** lol.. So to get to the point he was putting 87 octane gas instead of 91octane... he didn't know... so i showed him the big sign over the fuel guage...lol lessoned learned :chairshot: ... my mpg is drastically low and slight misfire on cold start, almost seems like the cheap gas fouled my spark plugs, cars current mileage 243,xxx and running strong :)but notto its full potentional.... (HC 2 below state max on smog test) don't want to ruin the catalyic converter...probually did already but hey thats the Nature of The Beast ^Thanks Cali^ Basically tired of the distrubutor style ignition want to know if anyone has swapped a newer 98-00 sc400 upper half. for instance 95 sc400 4.0l block, upper end/intake 98-00 (DIS 250hp to 290 hp) or knows any swapped done maintaining factory used parts/look but making 300hp+...or atleast over 250hp.. since i do have access to Toyota/Lexus parts/info looking to do a Factory Swap...no mickey mouse wiring and scratched parts.. thanks for reading and info will be greatly appreciated..