This R33 GTR build includes an extended sump, (same as yours I believe) HKS oil pump, oil restrictors and accusump. I'll find the page for you (although the whole thread is interesting) ...its page 47, post #701 and on the next page post #713 there is a link (reproduced below) that he made on the operation of his accusump.
http:www.skylinesdownunder.co.nz/forums/index.php?topic=66378.690
Http://youtu.be/uhRfUegqwxg