'68 shortbed BBC swap questions

[FstCarsNGuitars]

First off I'm aware there are several threads in regard to swapping a big block in our trucks but I have a few questions that I can't seem to find answers to. I'm currently wanting to find out if the perches I have will work or not (I will post a pic) I seem to be getting two different answers on this. I've been told that my current towers will work as long as I'm using tight clearance headers. I've also been told that I would need to find '72 and up perches to use stock mounts. My dilemma is that I want to build on a budget, so if I can use stock mounts, I will. At the end of the day if I need to dish out the money for aftermarket mounts, I will...just want to know what choice would benefit me better.
*Also, if the perches I have will fit, what mounts will work?

Any help is appreciated guys, thanks!