It's a bit of a challenge to find sources of non-commercial scion peach wood in the Dallas area, which you may have found out already. A search on "scion peach wood" brings up some possible sources, as well as people who may be interested in swapping varieties.

Regarding varieties and topworking, here are a few articles from Texas A&M regarding technique and best varieties for your region:

http://aggie-horticulture.tamu.edu/fruit-nut/files/2010/10/peaches.pdf

http://aggie-horticulture.tamu.edu/stonefruit/rootstock.html

http://aggie-horticulture.tamu.edu/stonefruit/topwork.html

One last note: It doesn't come about until October, but there is a fruit conference put on by Texas A&M that you may find interesting as well. Below is the link to the 2015 program schedule:

http://aggie-horticulture.tamu.edu/fruit-nut/2015/08/03/2015-texas-fruit-conference-program-schedule...