oils and lubricants

i need input on what is the final opinion on regular oil, blended or full synthetic for triumph tr6 engines. a close estimate is 100,000 mi's on the engine and i don't know the status if it was ever rebuilt.
also, can blends or sythetics be used in the manual tranny and rear ends of these cars. i'm a big believer in blends and sythetics on more modern equipment, but no one seems to give good advice on tr6's.
thanks in advance
:popcorn::popcorn: