Thanks for the reply!
One development since my last post, I spoke with a person at LinkLabs, they mentioned it's possible to change the SAW settings on the LoraWAN Raspberry Pi Gateway to setup the SAW filter for 915 MHz. I'm going to try to get more information about this, will post here when I do. Ideally I'd like to see if I can get the schematic prior to ordering. They also pointed me to the github project here which targets their Raspberry Pi Gateway and which was introduced in a forum thread at http://openlora.com/forum/viewtopic.php?f=4&t=36.
I've also spoke with Multi-tech about the MTAC-LORA-915, they confirmed that they believe the plan to use this card with the instructions at mirakonta/lora_gateway will probably still work.