It's quite tough to get ECE in the general category with this rank as IET Lucknow is supposed to be the top college after HBTI has become an independent University. Having a few friends from IET Lucknow and read online reviews here are some tips for you.
I would suggest you apply for the Electronics and Instrumentation Branch as well. I also advise you to accept any branch offered in IET, as you'll get a branch change option in the second year if you'll be in the top 3 among your class peers.
Cutoff for B. Tech for the general category (2020) –
Branch | Cut off Rank |
Electronics and Communication Engineering | 193-508 |
Electronics and Instrumentation Engineering | 582-1132 |
Since there are 3 rounds of counseling available, you should perform well and remain positive.