Main bolt difference

Has anyone tried to put a windage tray on a 273 and found the 340 main bolts too long to use? I don't remember having any problem in the past with 318's, 340's, and 360's, but, this particular block is giving me pause. I noticed the windage tray bolts were longer, than the stock 273 main bolts so, I checked the depth of the holes and there seemed to be enough room so that the bolts wouldn't bottom out. I then ran both a cutting tap and bottom tap into the block holes to clean them up. 3 of the 4 bolts will now tighten against the main caps, but. one won't. It's like it isn't tapped deep enough, or, at least as deep as the other 3 since they seem to work. I've run the taps as deep and tight as I dare several times to no avail. Has anyone run across this before? I guess I can just use some hardened washers under the heads of the main bolts, but, I don't know if that is going to hold the windage tray off too far, or have it interfere with something.

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