Anyone witty peeps here know how to make an FJS M4 CQBR into an M16A4?

https://preview.redd.it/suyy1ps43eif1.png?width=1027&format=png&auto=webp&s=06b1f0031e3191fb5a6e41148366395bf6f0b77f

Hey ya'll! Me and my seller buddy are about to make one of the most... weirdest choices ever. Since not one seller in the Philippines sells an M16A4 Gel Blaster (without visible screws on the right side like a pellet gun). Me and my seller friend (who's got connections in China for his supplies) are about to make an M16A4 out of an FJS M4 CQBR. Him requesting a supplier to mod it out to be an 80% Metal Full sized M16A4 as much as they can before shipping it to us here in PH.

Anyone got an idea how you'd do it personally at home? Quite curious if anyone here has done a similar build before, and if so what did ya do and what parts did you have to replace the stock parts with? I have my own ways of course but want other's opinions on this matter.

Thanks!