Mk1 registration number

Hi everyone, 
I'm hoping that one of you guys may be able to help me out here , 
I bought a cat c mk1 GTI a few years ago with out a logbook , engine , gearbox interior , and lots of other bits but it was solid and I checked it out on hpi to make sure it wasn't stolen ( I had a few tax discs with reg on ) and checked chassis number all was ok .. 
so now Ive started a 1.8t conversion which has all gone quite well ( especially thanks to rubber Jonny for your life saving wiring write up ) . 
Now my problem is I cannot find any trace of the vehicle reg number .. I've moved units after the roof came in , soaking loads of stuff last year and think my paper work for the golf lost .. I've tried to hpi using the vin number and it shows all markers etc apart from reg , think this is because it was a cat c and siding have a vic check which is no longer a requirement, I've sent v62 form to DVLA but I need a reg number to complete!! Nightmare …
So can anybody please find a registration number from a vin number ?? 
Thanks in advance and sorry for rambling on lol

I'd try VW to see if there is a link between the VIN and the REG but I dont think there is one.

Maybe better off getting it re registered that way you'll lose the previous write off status as well

That's a thought ! Try Vw , haha didn't even cross my mind to do that ! What I did do was spend half the night trawling through emails looking for the email from the guy I bought if from .. don't know if he would remember the reg or even knew it but it's worth a try I suppose .. 
so if I re registered I would lose the cat c marker ? 
I'm going to have a look now at what's involved 
Thanks for your rapid reply too .. 
cheers 
Mark 

You might not lose the Cat C marker by registering again. You may end up with a Q or even have to do the IVA. Did you have the physical registration plates when you received the car.  If the car was on a cherished registration and removed at that time that may be a reason you might not be able to source the registration. You could always fill in a V5 application on the chassis number and see what DVLA come back with.

Hi vic   , I've  had the reg and hpi check when I got it and it showed cat c . It wasn't a  cherished plate either .. I can't even get the old hpi up as it was done before all the data protection came in on phone apps etc so all my hpi search history is lost ! Infact the app I used has totally changed . 
I have messaged the guy I bought it off but no response yet ! 
It will end up a track car if I can't get it sorted . 
I've sent  the v62 form off this morning but it says if all details In section 1 are not complete it will get returned,  first box to
Fill in is for registration number haha .. I've a picture of the number too . 
I've tried all kinds today , car spares shops , searched all my old photos as I normally have something but not a sausage ! 

Not even a bean of paperwork with the registration number on? Have you googled the registration number?

Nothing , lost all paper work with a roof leak , there wasn't a lot as it has been a track car . I had old Tax disks . 
I can't google reg as I don't know it lol 

Shouldn't end up on a Q plate, depends how you go about registering it.

Im currently registering a motorcross bike for road use and I have had to obtain a certificate of newness from Honda UK by sending them the engine and frame numbers, from this they can confirm ID of the bike and produce a certificate of such.

This may be the case with VW, the difference is without the certificate I will get a Q plate but with it I will get age related

I've been reading through the IVA testing as maybe that's a possible way to go about but I definitely won't be putting it on a Q  plate . There's no point .. I believe insurance would be stupid! 
Cheers