As an individual in 1970, I'd have voted Conservative. With the benefit of hindsight, I'd have voted Labour to keep Heath out and to keep us out of the EU, although perhaps the Conservative Party needed the Heath disaster to steer us away from that path.
Well, I think it would've depended on what constituency I was in. My family came from Devonport, so if that's the case, I would've voted Labour because I like David Owen. I don't think I could've supported the Liberals because of Jeremy Thorpe (with hindsight). So I'll say Labour.