Jim,
x2 on the other posts, great build.
I've run my home grown computer the Gonkulator on Tom Lowe's 292 dyno tests, so here is what I compute for your build. My main caveat to these numbers is that I have no dyno data yet with Langdon's cast headers, Tom Lowe plans to get some during his next dyno series. So for your engine I calculate:
Torq 258 at 3500
Powr 226 at 5000
Since you describe the engine fading after about 4300 I think something is wrong with its tune. I like about 36 total advance, 26 seems way too low. Or, another easy thing to check - here is the Gonkulator if the secondaries don't open on your Holley:
Torq 248 at 3200
Powr 203 at 4700
If this is happening, and advance is too low as well, that could explain what you're feeling. Put a paper clip on the secondary diaphragm rod, slide it up against the housing. Then, go out and floor it thru a couple gears. When you get home, you should see where the paper clip had to slide down on the housing IF the secondaries opened.
Right now I am running a stock, tired 250 with a Clifford 4v intake and various 4v carbs (Holley and Autolite). The mismatched engine feels like a sick dog until about 3500 and then it feels like you flipped the "NOSS" button. I have to watch the tach to keep it BELOW 4800. So I think yours should be pulling to 5000 if everything is tuned right.
Again, great combination of parts.
