Not sure Shortleaf can handle soil pH of 6.8. Was under the impression that their highest pH was 6.5. Perhaps others can verify that.
Loblolly should be able to grow in soil up to 7.0.

Plant half of each ;-)

Not in an even grid mixture though, little clumps of one here, the other there, and so on.

Resin

I planted some of the Bastrop area Loblollies in north Louisiana several yrs ago. They didn't seem to be growing any better than the native Loblollies. The state of Tx used to sell them when they ran the e. Tx. nursery. Might write the state forestry dept. to see if they can tell you who grows them now.
I always liked the look of the Shortleaf pines better, and they will come thru an ice-storm with considerably less damage. There are several towns around Stephenville, Hico, DeLeon area where people have planted what appears to be Loblolly pines in town. They appear to be doing well and are up 40' and higher. Rainfall is similar I think to where you are. Also the soil in that area has transitioned from blackland clay (alkaline) to reddish sandy/clay (probably neutral - slight acidic). Good luck.

being hardcore MI ... and TX may as well be mars.. i have been holding on ...

but resin finally said it ... go for it ...

it sounds like you have the property to do it ...

when it all boils down.. its all about micro climates.. and that includes soil ... weather.. etc ... all the variables ....

we can all gaze at out navels.. drink a 12 pack or so ... and come to a multitude of conclusions.. which will be basically worth the empty cans ..

just plant things.. and find out.. what will grow in your area... in your soil.. with your weather .. etc ....

and then you become the next TX expert ..

if you dont.. then we are just left with scot.. lol ... and i swear.. he has tried EVERYTHING ... and that is why he is our esident TX dude ...

definitely go with rather cheap.. one to 2 footers ... and see what happens.. you have a small investment.. and we all will learn... presuming you report back ...

ken

Thanks for the advice. I'll probably plant a few of each and see how they end up doing.

I am still curious about the Bastrop loblollies vs the normal loblollies. Ideally, I would want at least one of each: Bastrop, regular loblolly, and shortleaf, to compare all of them. I'm going to keep trying to find a source for some seeds or seedlings from the Bastrop area.