well you are going to have to either have to extend the engine out the front where the radiator is , or you will have to lengthen the front shaft and shorten the rear shaft.
i think the old inline six has the same bolt patten as the
4.3 bellhousing but i could be wrong. if so , you will have to see if there is an adapter to hook the 231 up to the
original tranny. if you pull the tranny from a k5 blazer
with an inline 6 , you could see if a 231 can be clocked
to have a driverside drop. good luck.