Exorcism in 3rd Edition? Opinions please!

[Themike]

What do you think of this for a exorcism for a group of 7th level players? Wanted to make it difficult and long to reflect the momentousness of the undertaking, but not impossibly difficult.

Since it might be possible for the spirit/demon to resist am going to allow them to use scrolls as needed.

Exorcism

DC 16 if subject is willing to be exorcised
DC 19 if subject is resisting
Spirit/demon gets to make will saves flat d20

DC Reduction
If spirit is to be banished from plane then an open portal will reduce the DC by 3
If spirit is to be forced out of subject and into an appropriate object DC reduced by 2
If subject is restrained by blessed, silver or iron chains reduce DC by 1
If subject is on hallowed ground then DC is reduced by 1
If subject is immersed or dowsed in Holy water then the DC is reduced by 1

Assistance
If multiple clerics are acting together to perform the exorcism and they serve the same deity or their gods are within 1 step of alignment then-
If 2 Clerics both roll and the better of the 2 rolls
If 3 or more then the DC is reduced by 2
If the Clerics’ patrons are not within 1 step of alignment then the DC is increased by 2

Conditions
Must not be in combat
Subject must be present
Cleric(s) must be willing
Cleric and subject must be able to hear one another (loud river, thunderstorm, blowing wind)
Must be performed meeting at least one of the following-
At dawn
At dusk
On consecrated ground
On a Holy day

Process
1) Cast Magic Circle Against Evil
2) Activate portal inside circle (Dimension Door or Gate) or have the item to house the spirit in ready
3) If subject is unwilling Cast “Emotion- Hope”
4) Cast Dispel Evil
5) Cast Bless on subject
6) Cast Dismissal or Banishment

Subject loses any bonuses for being possessed and is weakened for 1d4 days.
Subject gains a +2 to Will saves

[Thugorp]

I think it matters what exactly is being dispelled. I am a prone to thinking that this might be a bit of over kill... but it does depend on what is being exorcised. Is it a gost a demon, an abiration from the outer-realms? Could we get just a bit of context?