Looks like a august 1966 motor. HO should be a 300hp 327 with a powerglide. Ho also corrisponds with 1966/1967 corvette motor. BUT, T0825HO. I believe the T means it was produced for a truck. Which is very possible, but I dont have any books to break down the truck #'s. Hopefully someone can help me out with that part.
O by the way. Those 462 heads arent to bad. The performance guys out here would like a set of those!