There's a ton of stuff I disagree with Calvin about. I'm not a Presbyterian, nor a paedobaptist and I wouldn't have burned Servitus. Calvin is right on penal substitution but wrong on Christ's descent to hell. The cross was His hell.
If Christ does not have to bear the full weight of the Father's wrath against sin and sinners, why would He refuse an analgesic? No, the cup He must drink is the cup that the Father's has given Him:
'In the hand of the LORD is a cup
full of foaming wine mixed with spices;
He pours it out, and all the wicked of the earth
Drink it down to the very dregs' (Psalm 71:8).
'Awake, awake! Rise up, O Jerusalem,
You who have drunk from the hand of the LORD
The cup of His wrath,
And who have drained to its dregs
The goblet that makes men stagger' (Isaiah 51:17).
The Lord Jesus drank the cup of the Lord's wrath, and drank it down to its dregs. As our Substitute, He must suffer the righteous judgement of God against sin, and there are no analgesics in hell.
I have not forgotten that I have promised to open a new thread on the Biblical evidence for Penal Substitution. I should be able to make a start very shortly.