Has anyone did a build off of one of these? I saw one of the quad railed uppers and it looked solid. Is there anything to be cautious about?

I was thinking:

megalithic quad railed upper
Mega lower
Lmt 308 receiver extension
Lmt action spring
Lmt BCG
Some form of Geissele trigger
A 16” rifle gas stainless barrel


Any flaws to this? This would be my first 308 build. The cost would be within $500 of a used MWS so would that be the better route? Any input or advise would be welcome.