Just had my HKS sports turbo re-cond and was planning on using a different pipe set up, but have hit a bolt clearance problem.
That for the the oil drain pipe and the bolt in the way. I thought I could rplace it with a button head allen key bolt to give me that few extra mm of clearance I need.
Poor shot of button head bolt but my bolt shop said its a UNC thread so not available.
Are they available in the U.S.
Or do I grind it down a bit, or can it be tapped for a metric bolt like in pic but not mach space to work with

That for the the oil drain pipe and the bolt in the way. I thought I could rplace it with a button head allen key bolt to give me that few extra mm of clearance I need.

Poor shot of button head bolt but my bolt shop said its a UNC thread so not available.
Are they available in the U.S.
Or do I grind it down a bit, or can it be tapped for a metric bolt like in pic but not mach space to work with