from oil cap their is a metal tube going down. that should be cut off and pinched. Problem with it is that it sucks dirt and grime. Yes the box at the top generally filters the junk out but some gets past inevitablly. A few options here are;
A. Put a small filter like the pic below on the oil cap.
B. find a oil cap that can breathe.
I prefer the filter version as it catches all.
You can find these about 2-3 inches in size.
As for doing the filters on the valve cover you have to do it on the upper end and extend with some tubing. Not the end of the world either way just a bit to improve overall long term performance.
Anyway, Open up the ports. its easy just a bit time consuming. Open up the exhaust manifolds again easy to do just time consuming. smoothing these out will assist with performance as their is less resistance. Same with intake end castings. Never go chrome or any other shiny material on the engine. yeah its pretty but it will F the cooling design of the bug motor up. To be real you want to keep all the aluminum and crap that was around the engine but with an open engine area on a trike that looks ugly and people want pretty. best color to use is black as it has a better heat disbursement ability. note that when VW made an arctic adition they used chrome gasket covers and everything else and for hot areas they used black or aluminum.
and please dont ever ever use a 1835 time bomb.
heres a trike simular to the one you showed.
