you might not be able to find a top shift t-case for much less than what Marlin offers the conversion for. when i did my duals i did what you are going to do and went with 23 spline and MC08-R10 and twin stick except for i have a forward shifting crawlbox. you are going to be taking the entire case apart anywars so it wouldnt be any more work to convert to top shift, and its easy too! the shift rails come pre clearenced for the gears and everything.
