I recently bought a mid 80's 12-speed Raleigh Technium 420 for $45. I've removed everything except the cranks. I want to convert it to a singlespeed. I'm gonna buy Shimano Sora brakes and brake levers. I'll keep the Sakae dropbars. The crankset is also Sakae. I know nothing about what common chainring size people use, chain and freewheel. I'm gonna have the [LBS] put it together for me. Unless you think I can do it with the right tools. Any advice will be greatly appreciated.

Raleigh Technium