1972 20' Volvo straight 6 - original? Advice?

[CRSeacraft]

Hello,

I'm a Shamrock guy (www.fishtheclassic.net)- I have a 1980 20' walkthru - but I have the opportunity to purchase a 1972 20' Seacraft with a volvo straight 6 (with 3 carbs) mated to a volvo 280 outdrive. She runs and shifts great but I know these Volvo's are old and parts are expensive and hard to come by. Do you think this engine is original? Would it be hard to convert to an inline mercruiser in the future? Any advice is appreciated since I'm a newb Thanks!