I bought and used a blanket on my last car I built, way better than the shields IMO

I managed with a 69 B body with no mods to the trans tunnel but I did mod the shield and never got the boot at the track for it.I bent at a 90 where the bolt tabs are on the shield[1"+] in and when in the car it buts against the firewall.I will get so pics if you like.

I don't know what your ET is but you might look at the CSR shield, it takes care of the flywheel and trans. As far as I know there is no blankets that cover the flywheel area. If you don't go the CSR shield route the JW Bell and trans blanket combo is probably the safest and easiest.

I had to do some pretty extensive massage work to get a CSR shield on the 904 on my a body. I didn't have to cut anything out but I had to use an air hammer to make the whole right side of the tunnel larger. I would imagine an E body to be easier but I have no idea.

CSR shield here, 727 E Body. Had to flatten the bulkhead / floor pan seam for it to fit
HTH's