Forgotten heavy bands from late 60's to early 70's


Have been a fan of hard rock/metal since high school. Always liked the heavy/physcadelic bands equally to the metal bands I grew up with Ozzy-Maiden and Scorpions ect. Recently on Youtube I discovered some heavy/physcadelic bands I was unaware of. 13th Floor Elevators-Five Day Rain-Probe Direction-The Hook and Vahalla. Are these bands albums worth persuing? Feel free to mention any other band that deserves to be heard. Look forward to your responses.
dayglow
Here's some (on the more obscure side) heavy LP's I'd recommend you to check out for starters...from memory so hopefully correct...

Blue Cheer - Outside Inside (1968)
Bloodrock - same (1971)
Lucifers Friend - same (1970)
Pulse - same (1968)
Highway Robbery - same (1972)
Demian - same (1972)
Bolder Damn - Mourning (1971)
Night Sun - Mournin (1972)
Sir Lord Baltimore - Kingdom Come and same (1971-72)

...and if you dig this - also check Masters Of Reality - same (1988 i think)...
Some more familiar names from the early 70's:
Uriah Heep
Try Live, Demons and Wizards, the Magician's Birthday
Wishbone Ash
Try Argus and live Dates.
While not as acid drenched as 13th floor elevators, these two are definately very heavy. Uriah Heep Live is an all time classic and Wishbone Ash was one of the first bands to use a dual lead guitar approach which definately inspired Iron Maiden, Priest, etc.
Not a Heavy Metal band but a Heavy Classic Rock band, Spooky Tooth made a classic album, "Spooky Two", great album. That's the only one I can recommend. They put out others you might want to explore if you like Spooky Two.