I put a 402R Roush engine in my '03 SPF 1580. My experiences are similar to those noted. An initial
oil pan gasket leak was caused by my installer, yet Roush quickly helped me out and overnighted an entire new pan and gasket! I still see a small bit of real seal drippage, but not much. Another installer said, "...hey what do expect, it's a Ford 351...'! My engine has run extremely strong from day one, without a single problem and it's wonderful on the open road. I've got a few thousand miles on it now.
Don't accept the "book rate" on the Roush engine. Haggle a bit and you should see some reduction.
I run 93 octane here in TX, but could only get 91 in CA. Both have proven to be no problem and I've never experienced pinging.
I love their engine and workmanship and the Superformance is tops for a replica.