318 or 360 gasket set ?

well.....a bit of both. the intake and exhaust ports will be bigger, youll need 360 gaskets, but the oil pan set will be different for a 318. a fel-pro FS8553PT-8 will be a gasket set for a 318 like my 87 cop motor, vin "M" (thats the key), wich has exactly that, a 360 top end on a 318 shortblock. dis-reguard what fel-pro says it fits, it will work with what youre doing. cheers.