A true RetroTech Urbie would use a 75-rating engine to go 2/3/2, and would have 18 tons for armor and weapons after the basics and jump jets. Matching the R60L takes 6 tons of armor, while matching the standard R60 takes 9 tons.
For ICE power, current rules prohibit that on BattleMechs, as I recall, so now we're talking IndustrialMech Urbie. A 60 ICE is 3 tons, so now you're at 13 tons base without environmental sealing, or 16 tons with it, moving 2/3/0. Upping it to 3/5/0 to compensate for the lack of jump jets puts you at 16-19?tons base. Neither comes with heat sinks.