If I misunderstood your question, please let me know.

The UTS would refer to the Ultimate Tensile Strength of the material. As this is typically 1.5 times the Yield strength, I would assume that the 35/45 refers to 35 - 45 tons per square inch. (78 - 100 kSI) This looks a bit high for the chemical composition stated, but is not impossible.

Are you sure that it is BHM and not BHN? If it is BHN, then it refers to the Brinell Hardness Number. This correlates well to the 35 - 45 tons per square inch UTS given. (A standard table shows that 152 - 207 BHN is equivalent to 75 - 100 kSI.)

Welding this should not be too difficult. If you can get away with a weld strength of slightly lower than the UTS, then using a 70 kSI consumable should be OK. (e.g. E7018; ER70S-6 etc.) If you need a matching strength weld, then use 80 or 90 kSI fillers. Pre-heats would depend on the section thickness. As you are talking about a casting, it may be rather thick. In this case, you should manage with a 150°C pre-heat.

As you are talking "repair", there can be complicating factors such as product contamination. You will have to find out in what service this casting was. In general, when repairing a contaminated part it is better to use a "fluxing process" such as SMAW or FCAW. Also use low dilution techniques, because then less of the contamination ends up in the weld metal.

I hope this helps.

Niekie