I'd blow a grand on a built motor from a specialist..... if I had a grand to blow on a motor. It's a built motor, so it should be powerful and reliable. Like 200bhp from an NA 2.0 motor powerful.
Thing is a standard 70-100k motor built by VW will also be powerful and reliable, because it's been assembled in effectively clean-room conditions from bloody expensive parts. Not AS powerful granted, but probably more reliable.
It all depends what you want from the motor. Where your priorities lie.
£500 getting an ABF on Digi 3.2 running all day at 165-170bhp, plus a couple of £250 bare motors on the shelf for when the first one goes pop.
£1000 on a built motor. Oh and then £500+ on ITBs and £300 on a stub manifold. Oh and then £500 on management. And then another couple of hundred on rolling road time, getting it dialed in.
But £1k for a VW motor running on 1950's induction technology?
Are you f*cking mental?