That inner-to-outer cowl panel (brace) is notorious for not fitting well. If it fits OK other than the holes, then just drill the holes out to match the holes in the outer cowl. I see you haven't gotten the inner cowl fit yet. I'd recommend you get that fitted in place before you weld anything else in.

Is the outer cowl panel new also?


Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.