Hey there Shane!
I went ahead and compared these two plans side by side and what I found was the SSB 2 HV has a significantly higher weekly TSS. This is because you are not doing any swim or run workouts along with your cycling workouts. So, if you are looking for the biggest jump in FTP and want to mainly focus on your cycling fitness for now, I would suggest sticking with SSB 2 plan and maybe sprinkling in some run and swim workouts here and there. You could even choose a Mid Volume plan so that you have time for a couple swim/run workouts each week if you would like. That said, if you want to train all of the disciplines for your IM evenly, I would recommend the Full Distance Tri Base plan where you will average 400-500 cycling TSS and have dedicated swim/run workouts on top of that.
In episode 122 of the Ask a Cycling Coach Podcast, we talked with Andrew Talansky about why he made a switch from road racing to triathlon. He talks about all of the changes he has to make and how to cope with the differences. You can check this out here: