Try replacing the word "conscience" with the phrase, "artifact of the Fall, a thing of man's defilement, of man's spiritual death in sin," in the following verses.
Ac 23:1 And Paul, earnestly beholding the council, said, Men and brethren, I have lived in all good conscience before God until this day.
Ac 24:16 And herein do I exercise myself, to have always a conscience void of offence toward God, and toward men.
Ro 9:1 I say the truth in Christ, I lie not, my conscience also bearing me witness in the Holy Ghost.
2Co 4:2 But have renounced the hidden things of dishonesty, not walking in craftiness, nor handling the word of God deceitfully; but by manifestation of the truth commending ourselves to every man's conscience in the sight of God.
1Ti 1:5 Now the end of the commandment is charity out of a pure heart, and of a good conscience, and of faith unfeigned.
1Ti 1:19 Holding faith, and a good conscience; which some having put away concerning faith have made shipwreck.
1Ti 3:9 Holding the mystery of the faith in a pure conscience.
1Pe 3:16 Having a good conscience; that, whereas they speak evil of you, as of evildoers, they may be ashamed that falsely accuse your good conversation in Christ.
I actually agree with some of what you said about the conscience. It is only an instrument, like the emotions, and even the mind, which can be good or bad, which Scripture plainly teaches. But as an instrument, like the mind, and all other faculties, they were given by God, and God does not give bad gifts.
By the way, the words "convict" and "conviction" do not appear in the King James version. (They may appear in some other version which are more liberal in their use interpretation rather than translation, e.g. the translation of the word sarx (flesh) as "sinful nature." I haven't head any Calvinist's object to this mistranslation, however.)
Conviction is derived from the same root as convince, and to be convicted only means to be convinced of some idea as true. It would be correct to say as James relates, the devils are under conviction there is one God.
The idea of conviction, or conviction of sin, is a rather recent theological or evangelical concept. The work of the Holy Spirit is always expressed as revealing the truth of Jesus Christ. (I know that truth will also convince one of their own sinfulness and unworthiness, as a result, not the purpose of the revelation.) I do not know when this view originated and if you have any incite into that I would be interested.
Hank