How do you identify a ford 302 ho motor?

One way is the firing order. The 302 HO has the same firing order as the 351. So, if the firing order is 1-3-7-2-6-5-4-8 you have an HO engine. If the stock manifold is on the engine, it will say "5.0 Ford HO". The exhaust manifolds were factory tubular headers. They had roller cams.