Hey! I have one of these in my garage that hasn't been used for the last 15 years. I'm thinking about doing it up - I've never fixed a bike up before so not sure where to start, I know I want to replace the suspension fork with a stiff one but haven't a clue where to start looking for one. Do you know where I should start looking/what size I would need please? It is a 19.5" frame. Thanks!