Get a real race bike. The old guys are racing mostly the same bikes the elites are.

Modern tracks are a lot different than back in the day when those retro bikes were raced.

Also - don't be too attached to cruiser - some guys love their cruisers, but I just can't get comfortable on mine. Feels unwieldy. But match it to your local track - if the guys your age are racing cruiser there, then get one.