I have thunderbolt 4 ignition. it has a magnetic pickup.... I can run the msd ingniton box with that distributor right?

Actually, a Thunderbolt IV does not have a magnetic trigger. It has a hall effect sensor, but it can be used with the blue MSD 6460 ignition.

it has electronic advance built in right?

Go to MSDs website. It has instructions on how to run the box with the Merc Tbolt IV distributor AND module.

should i buy a blaster coil shown in those pics?

Let us know if it makes a difference.
Im on the fence for adding one to my thunderbolt 4 distributer.

Yes, when used with a TB IV module. That's why the distributor uses a hall effect sensor. That's how the module recognizes engine RPM.

I looked closer to the diagram and yeah, i see now. so the merc module will take care of the advance and the box will change how it sparks and amplify.

I'm gonna get the coil shown and some plug wires and i will keep you posted as to what happens..

oh yeah, i was lucky enough to get my hands on a v8-hp module so all is good there.... but there is a rev limiter in that module correct? or do i need to buy the add on?

To the best of my knowledge, none of the TB IV modules have a rev limiter. Only TB V uses a rev limiter.

Far as I know to the 4's do not have a rev limiter.