rwd exhaust gasket and running rich questions?

[fitch9014]

which engine in the states, if either, matches the exhaust gasket(s) on the ca18det? i know, i know...i checked the faq and searched, sorry and thanks, in advance...

also, just in case, my car has been running quite rich because my funky stock turbo has killed two boost gauges and an oxygen sensor...should i keep driving it? i have a freshly rebuilt sr20 t25 to put on, but have been delayed by work/school requirements...i have other modes of transport (s10 p/u w/o overdrive, i love automatics ), but would prefer to keep driving my 240, as it still gets better mileage...again, sorry and thanks...