Chevy & GMC Vans

Thinkin of putting in 4.10 in the rear, how screwed up will my speedo, cruise control and ABS be and what are my options for fixing this??

Here's what I used to correct mine, JET Accu-Speed
http://jetchip.com/JET_Transmissions.asp

Thanks again LaGrasta you seem to answer most of my questions hahaha, maybe I should just PM you. Another $200, man these builds add up quick, holidays are the wrong time to try and build up the van, my plan is to acquire all the parts, then mod, seems a bit tougher to do than I thought right now, maybe by tax time