magnum cam extension from hughes?

I have the first picture kit-part number 7013-the third picture is part 7011, and can be used in conjunction with 7013-but 7011 bears a rather similar appearance to the cupped and keyed retainer in 7013, which I already have. I did finagle with that cursed little assembly for the better part of an hour believing, surely-I'd done something incorrectly or completely missed something. I used a stock replacement timing chain set for a Magnum (and I checked a standard LA timing set against it-no difference in drive hub thickness), assembled the s*** just as the second picture illustrates. The snout extension seems to go on as intended (beveled side in), and the offset ground key slightly engages the timing gear as intended. But, the cup washer or retainer or whatever the hell it is, if I put it over the extension with the key engaged in the slot I can get it to tighten down with one caveat...before I install the bolt, I can see about an 1/8" gap (possibly more) between the end of the extension piece, and the flat of the retainer/washer...this means to me there is likely a time where that extension will wander away from the cam snout and back into the retainer. As soon as that happens, the key will drop out of engagement with the timing gear and allow the eccentric to spin and tear up all kinds of s*** inside the timing cover.

I greatly appreciate your assist...I guess I'll have to buy ANOTHER $15 hunk of metal to make it work, or ask some machine shop to bend me over for an hours labor to knock off .100" off the end of that washer.

...as a sidenote, I did call Hughes...the gentleman who attempted to help me just basically recited the same thing I'd already tried and said if the instructions state I'd have to machine off some, then that's what would have to be done...