Ok, so i've got everything running from a battery, etc. and am at the point now where i need to get it into a case

Here's what i've done so far
I decided i wanted RGB on my portable so that meant modifying a US n64 to output RGB and play my PAL games.
To do this i simply removed the PIF chip from a PAL n64 and put it into a US n64


This chip is what interfaces with the controllers and the CIC lockout chip in the cartridge, by using a PAL chip (PIF(P)-NUS) it essentially becomes a PAL machine.
I also wanted RGB, i got this by tapping into "U4" the VDC-NUS pins and running them to an amplifier circuit i found here

This boosts the signal to an acceptable output level to drive a tv/screen

I also wanted an expansion pak in my portable, i did a few tests for overall power draw at 7.4V.
with expansion pak:
playing majora's mask ~ 900mA
playing mario 64 ~ 800mA
with jumper pak:
playing mario 64 ~ 600mA
It seems the extra ram in the expansion pak increases draw by about 200mA in normal games and about 300mA in those that used it!, since i intend to use quite a small battery, 200mA is fairly significant to battery life and also heat production.
An expansion pak also takes up room and is awkward to heatsink, so i replaced the 18Mbit ram chips on the n64 mobo with 36Mbit ram from a couple of expansion paks

The soldering is a little untidy because i used an iron and braid whereas hot-air would have been a bit neater.
But it works fine and games detect the expansion pak as normal, i did some stress tests with Perfect Dark multiplayer with 8 bots and there were no crashes for over 4 hours, this is longer than i would ever play the portable and i don't forsee it crashing after that time.
It still requires the jumper pak inserted, but it should be easy enough to hand-wire the resistors etc to the mobo without increasing the boards height.
This meant that current draw was reduced to about 700mA when playing majora's mask and 600mA on non-expansion pak games.
Here's a shot with my led-modded screen you can see in this thread

It draws between 900-950ma during gameplay altogether including screen and controller, and less when playing non-expansion pak games.
Sorry for the long post but hopefully now i've let the cat out of the bag i'll have more incentive to keep up work on my portable.