After a contradictory post about how I'm not a gamer, here are the three Forge World Venators after construction. I'm still working on the one drivers hands and arms (if you're noticing that). It turned out I could fit a Tallarn into the drivers seat without modifying the roll cage and raising the turret. I added Hellstrike missiles to the first one to hide the extra space created by the modification.
Technical: If you want to give your Tallarns Venators (which they deserve, after all), you'll need two blisters of Tallarn autocannon or lascannon teams per vehicle. The gunner loses his legs below the knee and has his canteen removed so he'll sit flat. The driver's lower body fits in without modification, but you'll need to trim off all the raised seat detail. Then saw off the models hands. Create forearms by putting the hands on the steering wheel to his torso. It works if you don't look too closely.