1500EUR is about £1150 so that would make the amp a little on the steep side. However, it looks to be in nice condition and all original. £1000 (1300EUR) would be tops imo AND I'd expect some Mullard or Brimars in there.
Dave, where are you seeing 100% stock PTP-wired SLPs for £750.00 ??? - they seem to be going more in the £850-900 region from what I've seen.
One thing is for sure, the price of all-original vintage Marshalls is still going nowhere but up. I thought I'd overpaid a bit for my '76 Superbass (£500) but it seems that's a £750 amp now.