Truth to be told, the factory Ford stuff will last forever, the aftermarket stuff is questionable. I don't think there is anything wrong with the ford coil and TFI setup - the real reason for the aftermarket ignition stuff is really fold older stuff and applications where more spark is needed due to RPM extremes and boost.
The aftermarket stuff sure does look pretty on a built engine though
I was going to build a short deck 69' 351W but ended up going with a F4TE block, but I was looking stroker at the time as well (kinda a PITA with that short deck). This isn't going to be a RPM based motor, so in all reality the stamped rockers would be fine - again, roller rockers are great for eekig out more HP with RPM. This isn't a track motor, so it isn't a necessity.
That cam in that 351W will work with the Mustang EFI, so you are good there. I would suggest a Pro-M meter as well, they are the industry best when it comes to MAF's.
With those heads and intake paired to a 351W there is no way you won't make under 350HP - don't really worry about that, you are after torque and a stockish 351W is a VAST improvement, anything on top of that is going to be serious fun. I'll eventually get to actually compare that - if you take a peek at my half cab build thread I've got an even nastier motor than the 351W setup to go into that and its going to be overkill.
You have a great set of parts and a great idea - I would say run stock ignition components for RELIABILITY only, its easy to throw money at stuff, but before you can have fun, its got to start every time and never leave you stranded. Factory stuff works and lasts-
The Mustang injection is easy to install - hell, most of the wiring harness can be put on the lower intake before you even drop the motor in-
