Looks like it's been a rebuild with a few tweeks on a small budget ... nothing wrong with that at all though !
The head is pretty much standard, but obviously reconditioned - and the bottom end has have a new lease of life. Pretty good platform to carry on with I'd say, change the cam and some mild head work and you'll be away ... also it's a PB engine code so get her chipped
I'd say the main reason for not putting the cam is purely the extra cost. If a cam was included you'd have to have a new ECU chip to raise the rev limiter and change the maps to make the best of it, then add a vernier pulley, getting the cam dialled in - it all mounts up! The bill probably would have been ?750 more easily.
Also the bill is dated 1997 - I'd hazzard a guess TSR's prices on MK2 engines have come down a bit over time!