727rebuild/ front pump questions

Thanks in advance for any help. My 727 lost reverse/high. Pulled tranny and dissasembled. Found high/reverse clutch pack destroyed. Input shaft, clutch drum not useable. Purchased a core tranny from a mid 80's van. (Non lockup) Can i use everything from input shaft to output shaft in my tranny? Old tranny date codes to 1971 but unsure if it has ever been into. Core tranny looks fresh. Everything in it is fine to the output shaft. Mike t