If you are making your own I would suggest that you steer clear of the rail design. In my opinion they are the biggest downfall of the T7 design other than the flat front plate which takes all the up and down pressure.
I had a T7 and after the front plate cracked I cut the front off and put it on a boom similar to this It extends a bit further than the original T7 and is flipped upside down so it a bit lower with a more natural (for me) hand position.
I wish I had a camera to take some pictures, they really are worth a thousand words.
And on using the T7 with a standard post: you just need to grind some metal off the front of the CroMo posts. I haven’t tried it with any other standard post.
EDIT: This is a better example
2nd edit: here is another idea, probably heavier but could potentially be used by shorter people and is really adjustable.