You’re already over half way there with the machine work and refinishing.

Get back with us after 30-40K and see if you get lucky. Nobody is saying that a $1K gun won’t be reliable. The marginal barrel fit and FCG fit generally won’t last as long as better quality parts with better fitting. You’re much more likely to chip a MIM (Springfield) sear, break a titanium firing pin, break slide stop lobe, or break a lower lug off a drop in barrel than you would something put together with more attention to detail.