By Socialist Revolutionaries I mean socialist revolutionary party. Also, would it be interesting if Lenin had led the socialist revolutionary party instead of the Bolsheviks?
(1) The Socialist Revolutionary Party was extremely diffuse. It ranged from near-Bolsheviks to near-Kadets. There is no way it could "merge" with anything; on the contrary, its tendency was to split, as it did after October with the secession of the Party of Left Socialist Revolutionaries. Not only would the mainstream SR's not merge with the Bolsheviks; they supported Kerensky and the idea of a coalition with the Kadets for far too long (as Chernov later admitted).
(2) Even the Left SR's would not merge with the Bolsheviks, though they aligned themselves with them for a while. Their disagreements with the Bolsheviks were not confined to Breat-Litovsk; they were also opposed to the Bolsheviks' policies of grain confiscation, the Committees of the Rural Poor, etc. In short, they were still a party that spoke for peasants, including middle peasants.
(3) As for Lenin himself, in his youth he abandoned Populism for Marxism and never looked back. One of his earlirst published works was "What the “Friends of the People” Are and How They Fight the Social-Democrats"
https://www.marxists.org/archive/lenin/works/1894/friends/