Brainstorming session for an MG74

I've been collecting parts/researching building an MG47 for a couple a years now, and I think I'm about ready to tackle this project. I have an 86 Romy G kit built into a faux RPK with a turned-down RPD barrel with type3 milled barrel bits on it (so I could leave the barrel a little bit thicker than if I had turned it down to us AKM barrel bits.) This would be great for an MG47 in that it has the added length to help with keeping pressure up longer for more reliable cycling than the 16" versions. Here's where it's at now:



So I got to thinking the other day, AK74 kits are fairly cheap right now and 5.45 ammo is really cheap right now, so why not try my hand at an MG74? The biggest hurdle here I think would be finding a feedtray/topcover that would work with 5.45 ammo. I figure that 5.56 is close enough to work, and the most common beltfed 5.56 I know of is the M249, SAW, Mk46, Minime, whatever it's called. But that presents a problem in and of itself. IE where to get the parts for less than a small fortune?

Anyone know who sells complete M249 topcover/feedtrays?