It's running! Brian Magee came to help me today and together we finished the last bits and pieces. Then.. we fired her up, she started first time and ran for 30 minutes (hoping not to annoy the neighbours - who should be at work anyway!). The only slight fly in the ointment was that the engine ran on for a few beats after I turned her off. Theories range from (1) ignition too far advanced, (2) timing tape/pointer not accurately indicating TDC, (3) timing chain not installed right, (4) plugs too hot or (5) perhaps fuel not up to the new compression ratio (10.5:1).
1) We checked the apparent timing with a strobe, it was 8 degree BTDC at 1,000 rpm which seemed a bit retarded as static should be 10 deg and dynamically reach 34 deg. advance at about 3,000 rpm (I am not sure where the ramp starts).
2) This evening I checked the TDC again by putting a piston stop in No.1 and manually turning the engine to the stop from both directions - it was spot on. The TDC on the balance wheel is TDC as shown at the pointer.
3) I also tried to check the timing of the cam versus the crank. I had done this before by measuring lift but not on the final build. I certainly did use a straight edge to check the alignment of the timing spots on the crank cog, on the cam cog, the cam axle and crank axle - I am sure this is right. Even so I measured the closing point of the exhaust valve on no.1 at 050 lift. It's difficult because the hydraulic lifters keep relaxing, but it come out as 10 deg BTDC. I am not sure how much store to put on this. As the crank gear has 21 teeth it would need to be 17 deg. BTDC to be one tooth out of crankshaft rotation. Basically I recall carefully checking this on the build and experimented with the old gears this evening - its so evident when its off one tooth that I am sure there is nothing wrong here.
4) I will investigate using different plugs. Frank had said before that they have changed to NGK plugs because Edelbrock changed the position of the plug hole.
5) I shall fill up with the highest octane fuel I can find - I probably have ordinary unleaded in at the moment.
I have a short video, but I don't advise anyone not on broadband to try it as its 11Mb big. Video of engine running.