Anyone here knows Beatallica? In case you don't: they take Beatles songs and play them in the style of Metallica. The lyrics follow the original Beatles lyrics but they are heavily altered to contain lots of fragments of and allusions to 'tallica.
Now how about "dreaming up" a band that does something like this with Opeth? Mix Opeth with a '70s prog band? While Camel would certainly be first choice for this I can't make any examples here cause I don't know any Camel

. So, I'll just take my fave '70s band which is Jethro Tull. I hope that at least some of you still know them. Here's some song titles, with original Tull titles in parentheses:
'Pethro Tull
The Locomotive Affinity (Locomotive Breath)
Cross-Eyed Melinda (Cross-Eyed Mary)
Song For Lopez (Song for Jeffrey. Jeffrey was a close friend and, for a while, also a band member of Jethro Tull)
Skating Away On The Thin Patterns In The Ivy (Skating Away On The Thin Ice Of A New Day)
Under The Wrapping Moon (Under Wraps)
Bungle In The Harvest (Bungle In The Jungle)
Songs From The Wreath (Songs From The Wood)
Living In The Bleak (Living In The Past)
Dirge For Luxury (Lap Of Luxury)
Too Old To Rock'n'Roll, Too Young To Bid You Farewell (Too Old To Rock'n'Roll, Too Young To Die)
Minstrel In The Silent Water (Minstrel In The Gallery)
A Passion Corner (A Passion Play)
Thick As A Robe (Thick As A Brick)
... And The Demon Of The Fall Never Sleeps (... And The Mouse Police Never Sleeps)
Gods, I could go on like this for ... well, quite a while. Hope someone finds at least something funny in this.