M1928 and m1a1 differences

[lrich]

Ok, i got some cheap Cybergun m1a1's from Kapowwe (bulk of 5 so i got them cheaper than the standard $40 each), and i wanted to try my hand at making one or a few into m1928's, or at least reasonable replicas. So please inform me of differences i overlooked, here are the ones i know, and in parentheses, how i plan to remedy them.
Upper Receiver
Different placement of bolt (fill the original with epoxy mix, sand flush, mill out bolt hole on the top)
Different bolt handle (lathe it out of aluminum bar, mill the U for the sights)
Different Sight "ears" (Use sheet aluminum, still deciding how to make the indents, or if to simply a little)
Different Sight (probably going to leave the Standard sight, Lyman seems to difficult to attempt at the moment)
Cutts Compensator (lathe again, possibly out of polypropelene for weight, will either be press fit, or pin fit.)
Different foregrip (will mill it)

Lower Receiver
Different selectors (i don't think making new ones would be worth it at the moment)
Slot for Drum (of course, since i am hoping to make the worlds largest midcap ;D)
Different Stock (ordering some real steels, will hollow them out for a mini battery on milling machine. )

If you could post things i overlooked, that would be great, thanks.

Lrich

[Bulllo]

Upper Reciever is square and flush with the lower reciever instead of the M1A1 having a skinnier reciever. Also, there are ribs in the barrel

[lrich]

i can't believe i forgot the ribbed barrel, one of the most obvious differences
Didn't notice the larger upper, but i'll fix that with a little bondo/epoxy and maybe aluminum tape for that "metal feel." Also, do you know if the receiver is taller, or just "fatter"
Thanks for the help.