Hi all just had an engine done and was wondering what sort of power I would get from it at the wheels. It's a 1275 20thou over light head work and 1:5 roller rockers 45 weber?

Depends on what dyno, all are different. Mine made 76HP ATW on a Dyno Dynamics with an RE13 cam, and 86.6 with the RE282. See other specs below.
But my head has big valves and ports, and the Redline manifold I spent 9 hours porting.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Like the good Doc says, it's very hard/ impossible to compare numbers from different dyno's in any meaningful way. For what it's worth (not much!), my engine which is more modified than yours, has a number of 75 Hp at the wheels at a place I would not recommend or go to again!

_________________
67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

At a guess - 50 to 55

An 80 BHP engine has about 50 Hp ATW.

What was a standard Cooper S at the wheels?

_________________
67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

From Memory 45 HP ATW, 78 HP at the flywheel.

I will do a search on here to see if there is any past discussions.

There is a bit about drive train loss here- viewtopic.php?f=2&t=66127&p=766424