OK, so, I decided to try to do this as close to a field refit as possible, and while the weight works, the criticals placement were off slightly from being a perfect swap.
The right arm AC/5 to blazer cannon was a piece of cake: the blazer is 4 criticals, 9 tons, while the AC/5 was 4 criticals, 8 tons, plus 1 critical/ton for the ammo. Meanwhile, in the left torso, removing the SRM-6 rack freed up 4 tons, but only used up 3 criticals.
In the end, I decided to keep the four heat sinks in the left torso, and just leave the blazer in the right arm, to keep the arm weight the same. The LT is over the original by 1 crit, the RA under by 1 crit, but weights work out exactly.
Wolverine WVR-6Y
IS experimental
55 tons
BV: 1,276
Cost: 4,783,507 C-bills
Movement: 5/8/5
Engine: 275
Heat Sinks: 16
Gyro: Standard Gyro
Internal: 91
Armor: 152/185
Internal Armor
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Center Torso 18 20
Center Torso (rear) 8
Right Torso 13 20
Right Torso (rear) 6
Left Torso 13 20
Left Torso (rear) 6
Right Arm 9 16
Left Arm 9 16
Right Leg 13 16
Left Leg 13 16
Weapon Loc Heat
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Medium Laser HD 3
Blazer Cannon RA 16
Equipment Loc
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Standard None
Standard None