PZ20 on my 3hp

I got a couple of the 407INT intakes from EC Carburetors. On the website the intake by itself states that it only fits blocks with 3 intake bolt holes. They list the same intake with a carb included and it says that there is a hidden bolt hole in the intake that will allow the use of blocks with 2 intake bolt holes. When I got the intakes they indeed had a hidden bolt hole but it does not line up with the hole in the block. Even if it would line up you would have to drill out the threads on the bottom hole in the block and grind down some fins to fit the bolt in from the backside to screw into the hidden hole in the intake. I have a steel sleeve, dual bearing, 12v electric start that I want to put on a mini bike. It has 2 intake bolts and I want to use a slide carb. I decided to see if I could get it to work on an old 3hp first before I went hacking away on my rare one. I drilled out the threads and ground down a fin to put in the bottom bolt and I notched the top intake bolt hole on the actual intake to get it to work. I like it. I think I might throw this on an old Sears Drover and mod the other intake for my 5hp.