Wobbly, B12 is recommended to be at the very top of the range, even 900-1000 for us Hypos.
When I tested all my vits and mins, my B12 was the only one not deficient, it was 663 I think. But I still supplemented with 1000mcg Solgar sublingual methylcobalamin. Next time I tested everything it was about 1100.
Although retesting when supplementing B12 isn't particularly useful in that you have to be off it for about 5 months to get a baseline and see what you are retaining, it does reflect that you are supplementing and I think it's useful to know if you are taking enough or too much. I reduced my B12 supplement to 5 days a week rather than 7 and now it hovers around the 1000 mark. So it's up to you if you want to get it up a bit higher, it certainly won't hurt.
As for handling the raw liver, what about using those disposable vinyl/latex gloves, I tend to use those when handling raw meat.