1) briggs flatheads have two pins holding the flywheel magnet in place and better casting. They dont blow up unless you go crazy
2) connecting rod will eventually fail if you dont check oil clearance on the crank journal, but its not a huge deal if you keep it relatively stock.
3) i wouldnt go for a honda clone carb, id acutally get on ebay and do a "pz20 carburetor" search and just use the pz20 carb. Might need the main jet drilled a tiny bit, but mine actually ran great straight out of the box and it was only like $13. Just needed to adjust idle mixture.
4) valve float on a flathead (l head wahtever you wanna call it) is not as dangerous as it is on an OHV head. If you hardcore float the valves on ohv you can drop a valve into the combustion chamber and it could completely ruin the head and block. You could bend the valve with piston to valve contact as well. With a flathead, valve float just doesnt have those risks. You dont risk dropping a valve EVER and you dont risk the valve contacting the piston EVER. Sure valve float is bad for other reasons, but you know a good 5500 rpm with a stock engine is okay in my book.
If you do keep the stock rod and it breaks dont come crying baack to us saying we said it was fine haha.
If i was on an extreme budget I would do the following:
1) swap out to a cheap PZ carb with venturi 2-3mm smaller than the intake valve $20
2) make my own intake adapter for the carb $10
3) advance the timing by 4 to 6 degrees and torque back to spec FREE (advance more for methanol)
4) see if i could convert the carb to methanol $5 drill bit set and some sandpaper if needle is too thick
5) port the intake and exhaust. General clean up plus the "inside edges" of the ports get radius-ed pretty good.
6) thread some schedule 40 pipe into the exhaust -$5
send it
