Clipper Cabrio Fuel tank

Hi

I have a square type fuel tank from a mk1 golf and a new larger type cabrio tank.

My cabrio has the larger type tank fitted, but can I remove this, without dropping the rear beam, then can I bolt the square type tank in there ?

Local garage wants £400 to replace the tank, labour only, saying he will have to take all the brake lines off, disconnect the flexi lines from the brake pipes.

Any help would be appreciated

Thanx

I'd be interested to know if you can remove the tank without dropping the beam too as i need to replace mine on my tintop, its leaking from where the two halfs of the tank have bin pressed together