Bad boy Mark,from my 'stock' of Porsche pics eh...copyright buddy
To the problem at hand ,each head as two drain passages,when the enter the block they 'Y' into one which drains through the main bearing girdle to the pan.I set up two heads to try & see how many qts of oil the heads retain,most of it runs out real quick BUT the area of the c/case baffle(in the valley) has a VERY large area,this connects behind the t/chain tensioners and two dains next to each of the cylinder bores,almost forgot,on the heads there are also drains each side at the front that drain back around the chain area.I think drilling & tapping the pan with 90deg unions and clear plastic ,'level' tube is the only way to prove this out,looking at the heads etc it seems hard for that amount of oil to stay there....FWIW !
