High Accuracy Pressure Gauge
Longacre Racing has recently released a nice digital shock inflator. PN# 50472 Longacre is a pretty nice firm making some quality products.
A special head on the inflator allows you to fill the shock, but not loose any pressure when the inflator is removed.
This gauge will read fairly accurately to 0.5 psi increments.
A high pressure inflating connector can be found online at such dealers as US Industiral Tool. PN# TP506 $48.00
Often, you will need to extend the shrader valve to get proper access to it. Motion Pro sells extenders for pretty cheap (PN # 08-0132, $2.95 ea.)
They are also available from US Industrial Tool in a variety of sizes.