New to vegan bodybuilding: Some questions-NSFW

Here is some background.

I have been lifting for 20 years. Mostly powerlifting . I am a big boy. Imagine Brock Lesnar and that's me. Just a big block of a man. I have been Paleo for a decade. Never abused steroids. Diet has been pretty Paleo strict with a lot of rib eye, tbone, egg, etc. I don't do the whole bacon and high fat paleo. I do quality meats and lots and lots of fruits and vegetables.

In the Past year I have had huge problems with UTI's and Kidney filtration. I was peeing blood, peeing hot etc. I was mortified and shocked to find out I had advanced BPH. The UTI was because I don't void my urine completely. As you can imagine this was a blow to me as I thought I was eating healthy. Also, I took tons of cod liver oil. This may be a coincidence but I stopped Cod Oil for a while and had no UTI's. As soon as I started again peed blood and had to do antibiotics. I was on antibiotics for a year so I can imagine my system is shot.

I am tired of this and will go vegan as my research points that societies that eat less meat or no meat suffer fewer BPH issues. A Chinese study confirms this. Farmers who were vegan are now starting to do SAD and getting BPH in high incidences. Sorry about the ramble.

I will be doing a Mcdougall like diet but want to add some protein. My questions are:

1) How much protein will a big guy like me need? I used to get 300-400g (I know way too much). SO what do I need? I want to aim for 80-100g . Will that be too low?

2) What is the best protein to take? I already started with Hemp but found if I go above 20g a day I have to go to the washroom about 20 times a day. Can anyone recommend a good protein? I like my shakes.

Anyways any input appreciated. I know I won't stay at 270 pounds. I don't mind losing weight as my joints seem to be complaining these days about my size. I am 6'3" so I might be good losing 30-40 pounds even if it's muscle.

Thanks,

Vega seems to be one of the best, its made from a combination of plant based proteins and its soy free as well.