Do we need a dedicated circuit for gas boiler (for heating)? I am thinking add two receptacles to the boiler wire circuit. Is this ok from code point of view? thanks.

I am running power from my meter (400A) to my service panels in my basement. One panel is 200A, the other is 150A. I have run two sets of 4/0-4/0-2/0 aluminum service cable from the meter through a 4" PVC sleeve in the concrete foundation wall. Unfortunately, where I was going to place the panels was too close to a sump pump pit. The cables are too short to reach an alternative spot to place the panels. As an alternative, I was planning on installing a junction box (18"x18"x6") where the two sets of service cables enter the basement. I would place a pair of 3-pole splicing terminal blocks in the junction box. I would then run a pair of 3" conduit from the junction box to each service panel. The distance from the junction box to the service panels would be 4' and 5.5' respectively. I know that ideally I would run new service cables. However, the ground is frozen solid here and won't be thawed out until April. It's a 200' run too. Are there any obvious problems or code violations with this plan? Thank you! Ben