Chawl room buying in mumbai

Hi.. Hanuman Mali here, I am planning to invest in property with keeping in mind a good returns after SRA project completion. After lots of research i found that investing in chawl room which is being plan of SRA will return high value within expected years of 3 to 5. as i belong to mumbai andheri area I have seen people had property in chawl but after getting SRA flat they have better property valuation. So I processed for purchasing in Goregaon west area which currently planned for SRA by Makwana group builder. I checked all papers(ration card, light bill,survey paper of year 2000 done by collector office,pan card, aadhar card,socirty reciept) all looks correct But when I asked for room purchased agreement then he said current owner is first owner and he is staying since 70 and later they got all documents from government in time and claimed to be owner of property just like other slum area in Mumbai. now I have ration card and light bill in name of owner that are 10 years old. so my question is there any problem purchasing this room considering that there will not be any issue while claiming for SRA project by replacing old owner. Agent is proving : power of attorney,sale of agreement,NOC,affidavit. (any things else should i ask). there is one more concern that electricity pole up there in chawl currently. agent saying polls are not active now and later after starting project polls will be removed but in such case can government will allow builder to go further building SRA project. Builder already have hoarding in chawl area saying this area will undergoes in SRA with registration no. keeping everything in mind property documents genuine and electricity pole should i go and buy it? Now i am seeking consulting help from for 1. obtaining sufficinet/ legal documents from owner. 2. needs assistance to verifying all documents/property 3. electricity polls existence issue. Awaiting you feedback