Padding 401k to buy back years of service.

Kind of an interesting ordeal I am in. I’ll try to keep it short.

I previously worked federal government. My new local government job has an option to purchase years of service from my prior employer. These years of service add 5.5 years to my clock. I am a PEPRA member.

These years will cost $105,000. There is no bi-weekly pre-tax payroll deduction plan. Using my 401k/457b is option to purchase said years. If I wanted to safely spike my 401k/457b (maxing out both totaling $45,000/year), which fund would be the best to park everything in? We’re with fidelity and I have brokeragelink.