In case it helps, here are some quotes from my 1975 Glastron owners manual for the older style "280" series drive, which appears very similar to your outdrive:
"An electromechanical lift operated from the drivers seat allows the operator to tilt the stern drive for beaching or trailering. The lift will allow the drive to remain in up position while in forward gear with the propeller turning at idle engine speed. CAUTION: Any speed above idle will cause the unit to slam to full down position. If the unit is slammed down hard, it is possible to damage the transom shield, drive unit or tilting mechanism."
"CAUTION: When running at slow speed in shallow water with great risk of contacting the bottom, it is recommended as an extra safety measure to release the retaining pawl for the outboard drive with the drive lift. NOTE: running in "reverse" cannot be carried out with the retaining pawl released. Release the retaining pawl as follows: Depress the "up" switch until the warning lamp lights up and then keep the switch in this position for another 2-4 seconds. This is to prevent damage to the propeller and outboard drive if they come into contact with the bottom.
1) Normally the outboard drive kicks up automatically if an object is hit in the water if the boat is running above planing speed.
2) You can run in shallow water with the drive unit partially tilted at idle speed only.
No reverse is available in this tilted condition."
Hope the above helps. Also, a SELOC manual (#3600) is available from BoatFix.com which actually has a picture of the duo-prop version of your outdrive on the cover. It would be a wise investment for you, IMHO...