Oil Pressure

i just finished putting my friends tranny in his 1992 3000gt SL.... now... we got it all put in ... and in the process we put a new Rear main seal... and oil pan seal...There are 0 leaks... however the oil pressure is really low untill he goes... but it drops back after idleing for a little bit... it seems really low... is this normal for a 3000gt?

mine does the same thing, if its in motion it should be at norm, but at idle it should drop some