If you want reliable manifold, this one would still be alive if a nuclear bomb went off nearby.
http://www.full-race.com/catalog/product_info.php?cPath=834_836_853_862&products_id=1433
If you want to run a GT30 on an SR without spending a million dollars on a built motor, you will need: metal headgasket, arp head studs, aftermarket ignition system (splitfire), at least stage 1 cams, 850cc injectors, engine management like others have stated vipec aem pfc, you want to have a good front mount and straight out exhaust