I'd think a real sideoiler would have easily sold for $450. Even just the block. Sure he didn't drop a "0" off the end of that price? For sure tho worth the time looking into it. FWIW lots of FE blocks have the rear bulkhead mold of the sideoiler cast into them. This carries the "66-427" cast into the block as well as the blank rear
oil galley/releif valve boss. Guys confuse this with the real deal all the time. Easy to understand if someone does not know lots about the oddities of the FE. As it is cast right into the block. Well let us know how you do and I hope it is a real sideoiler!!!!
G.