I blew an engine last summer and am having Dave Wesseldyke build me a couple of 540s out of my old HP500s. Should kick out around 600hp per side. I'm trying to figure out what to do about the ignition – whether to keep my existing thunderbolt or to go with MSD. I've heard strong opinions on every side of the issue, but am wondering what you guys think. If I go with MSD, am I going to run into lots of problems?

Daytona sensors. Hands down way better system than msd

ask dave and go with what he recommends.

I would use a stock GM Hei b4 I used MSD. MSD has left me sitting in the water. And not only that but I've had RF noise problems with MSD that was a nightmare figuring out.

Msd=suck

Stick with the TB IV. If you need more initial timing, run the V6 module. Yes, MSD sucks.. and no need to further complicate a simple build.

Does a Gen 4 Mercury ignition work in a Gen 5/6 application. If so, would you guys also stick with a Gen 4 Merc Mag ignition over a GM HEI or other?

MSD = my spark died

Gen 4,5,6 can all use the same parts. I have 2 dist and v6 modules I'll let go fairly cheap.

then you didn't have your connectors set up right.I posted a long time ago a diagram laying out the connectors.If and when the msd crapped out,switch a couple connectors and you were up and running on the HEI igntion.
Btw ,I ran my engines on a stock HEI and other on msd (560hp 454's) didn't notice any difference in performance.