If its still in your mates name he could get a logbook in a few days free of charge.
Don't get too het up about the mods,I had it before as I'd owned my own business for a bit and although I was out of the trading game a while some folk on here felt it their duty to "report" me for selling a car I'd owned and driven for a year.
Tbh specialist rs was decent about it all and got my ad re-instated and the car did actually sell through here.
I've had no hassle since as long as you stick to the 4 cars a year rule.