Currently Straight Talk only provides service for 3G based Vz phones. If you want LTE/4G Vz service, then you are currently out of luck.
Prior to July 17, 2014, Vz 4G/LTE was completely a post-paid program. In July, Vz provided 4G/LTE to its prepaid "ALLSET" service. I have seen rumors that Vz will provide 4G/LTE service later this fall. I am currently using ATT through Straight Talk, and while the service is good on the road, around my house, it is very poor.
So, bottom line, if you want Vz 4G/LTE service through Straight Talk, you are currently out of luck. If you have a non 4G/LTE phone (i.e. Vz phone without a SIM) then Straight Talk may work.
Hopefully, Vz 4G/LTE will be available in a couple of months......