If you want to convert to AK-105 :
The AK-105 looks quite similar to the AKS-74 :
http://world.guns.ru/assault/as06-e.htm
I think one of the main differences is the 5.45mm vs 5.56mm.
And the front sight assembly.
For the top cover, I guess you could put a non-ribbed AK-47 one in place. (I have one I can give you at Rawdon tomorrow if you wish to see)
And here's a nice shot of a VFC AK-105 if you want to compare.
I could be wrong, but I've been working on a '74 lately, and that's what I noticed.
I call dibs on your '74 flashhider :P