The Jag rear brakes are fine as far as size is concerned. Keep in mind the jag brakes were designed to stop a 4000lb. performance sedan so will easily stop a cobra.
Being inboard they are right in line to absorb heat being pushed down the transmission tunnel. Furthermore, excessive heat from competition driving will lead to premature failure of the driveshaft
oil seals. Ventilated rear rotors will solve the heat soak problem to the diff seals and keep the rear brakes working longer in hard driving.
Ventilated rotors are available from here in Aussieland. I got mine from here:
http://www.oztion.com.au/buy/auction.aspx?itemid=705868.
These folks have been selling these brakes for a long time and the kit contains everything you need.
Regarding bleeding, replace the caliper bleed nipple with a tube fitting and take a bleed tube from the caliper out to bleed nipples at a handy location on each side of the car. Just make sure it is above (higher) than the caliper. I've seen these lines in both solid brake tubing (preferred) and also in flex braided line.
You can obtain a remote bleed kit from here.
http://www.ward-engineering.co.uk/index.htm
Bottom of the page is a small reference to it.
Cheers