The difference between the 70's and now is the longer sleeve which now extends beyond the front block on the boom. Prior to the longer sleeve being introduced booms regularly broke in the vicinity of this block, but since it's introduction booms very rarely break.
So, are you suggesting you would not have a problem thru bolting completely thru the whole section as the orignal poster wants to do, sleeve or no sleeve ?
IMHO, two less holes in any spar is always a good thing, and you run the risk of over-tightening the bolt and collapsing the section
If only the builders would use the inhibitor and monel from the start.....
The method you describe will entail drilling a hole large enough to get the head of the machine screw through the tube wall of the boom. Given the thickness of the aluminum used to manufacture the boom, this may be OK. If it were me however, I WOULD NOT DO IT. The cost of a gooseneck cap is a small price to pay for not compromising the strength of your boom.
If you run a search, you will find some pics I posted about 2 years ago showing how I through-bolted all my eyestraps and the steps I took to keep corrosion to a minimum and strengthen the joint between the eyestrap and the boom. It entails using fender washers, nylon washers and a LOT of Lanocoat. You also do not need to purchase the kits from APS.
Hope this helps.
This certainly is an option. You can even stay class-legal as the tolerances allow for exactly this. The min/max measurements from the aft edge of the aft plug to the middle of the eyestrap are 59 to 83 mm for the aft sheet block, and 1641 to 1665 mm for the forward one.I would move the boom eye forwards and drill new holes between the worn out ones.