I'm sure @[deleted] told me it's only about thirty turn @[deleted] when he did mine, but as you say, most of those cars won't be 2.2 so lets hope they do a good job. One thing though, is the main timing chain a genuine GM one as that's what I was recommended to fit on mine with a GM or FAI balance chain. That price seem really really cheap so if they do it for that and do a good job then your on a winner mate. That price (150) won't be for both chains surely, the GM main chain is more than that on it's own, plus you need a new gasket and crank oil seal plus oil and filter. Hopefully they won't have to drop the sump if the front guide is intact. If it isn't then the sump will have to come off for cleaning out.