Paul 1st is an early GP frame, 2nd is a later GP( or 1975) frame -three variants of factory GP frames are known now. Early GP-no hole in gusset-perhpas some w/o gusset, then also early GP=two hole, then the somewhat more common four hole 74.5 GP and 1975 frame. ...then we have the wheelsmith LTR conversions, and other LTR conversions.
Fun, isn't it. You sent me the eng and frame #s-I think both frames are legit ofr 74 GP, while 400 eng is late 72/early 73-like was said -it could have been dropped in at factory, or replaced at dealer-or cases replaced at some point.
Personally, I don't think it should affect value of bikes as racers. BTW I got my # reference from the registry on Yahoo Maico discussion-more a documentation of what actually exists more than what series eng should have been with what frame. Bottom line, they are not Jap bikes-no definite production runs, no clear cutoffs-think of all the possibilites when a model changeover was happening, and there were parts to be used, or #s not used etc.
Hell, at one time no one thought a 427Ci COPO Chevelle existed, but it was built and exists.
James