A while ago I would've suggested the same thing, but now:
NO! 
Vengeance & Blackheart OUT! Yes,
IT SHOULD BE DARKER, but if anything, just retain the modern spiky-leather look &
STOP using plots/characters taken from the DK era (I'm saying this out of respect for DK purists

). I want the Johnny Blaze movies to be based more on the 70's era (with a few references from the new comic), only
with an added "modern" twist to capture audiences' tastes. I'm a long-time faithful of the 70's, and therefore I want them to focus more on Johnny's ensuing character development- as he grows to accept his new role as the Rider & learn to master controlling his own powers to be used against evil-
based on that era's story.
Here's a part I think would fit the sequel really well (preferably put in the setting): On one night, have JB stumble back into his old home- the Quentin Carnival, now long-since abandoned & left in ruins. He observes & laments the pitiful site as he recalls his own past- the mistakes he committed, & the day he met his "downfall". He looks up to the sky as rain begins to pour down from above (adding a dramatic effect to this sorrowful scene

) transforming into the blue-flamed Rider as he roars something like: "WHAAAT HAVE I DOOOOOONE?!!"
As he does so, a mysterious figure approaches him from behind..... is it a friend, or a foe?
(Hehe

t:, I got this idea as I was brainstorming my copy of issue 5 (vol. 5). Added changes, of course

, but still remaining true to it's "feel". I believe the sequel needs more serious moments like this.)
I want to see
Orb back as JB's arch-villain- complete with the same hate-filled relationship they shared in the comics. Include that memorable battle of theirs from classic series (to be used for the
climax) where a vengeful GR chases down Orb in an awesome bike race, throws the latter off from his bike (this time with a chain-attack or a shotgun blast) and, fueled by his own lust for revenge, starts pounding on Orb's head viciously & violently- nonstop,
NO MERCY! (those who read the 70's know what issue I'm referring to

), smashing his helmet in the process to reveal Orb for the pathetic criminal that he is. JB prepares the final blow, until he's stopped by....."the friend" (whom this time I want revealed to be the REAL Jesus Christ, to give us the immortal lesson that "
just because you have committed many wrongdoings in the past, doesn't mean that God has abandoned you."- making the overall 'feel' of the story more unique & full of heart. And of course, to repair what would've been a great ending to a story arc written by comic legend Tony Isabella

.)
Of course, attaining salvation doesn't necessarily mean that Johnny would have his curse removed. Rather, his spirit would simply be "
purified", allowing him access to his power's true potential- like the ability to change form by will (even during daylight hours) & assuming full control of the Rider. This also gives more emphasis on the element of
redemption strongly hinted at, BUT NEVER truly explored, in the first film. Finally, this gives us a proper explanation to what Johnny was trying to imply when he made that vow to Mephisto (in the first film), that "I will take this curse, & use it against you". This basically means
that he will never be a servant of evil, but an avenger of good; of innocents.
The only other thing, though, that I'd REALLY want them to work on with is
REVAMPING Orb's looks to make him more.... "appealing". For all the evil he's capable of, those who remember Orb know that he's just a redsuit-biker guy with a laser gun & a
giant eyeball for a head (actually, it was a helmet to cover his ugly, distorted face). I want them to give him a
more monstrous, intimidating makeover for the movies- something that makes him "stand-out" more.... like the kind of design that made so many of DK's enemies so cool to begin with.