bro, for me engine is 2nd part, the important is the chassis itself, if chassis not good or have been accident badly its would not satisfied your driving... some more if u could repair it, its wont give a perfect balance, the engine is more repairable some more u can change it even it involve some cost to it...
Find some chassis defect like any welding spot that suppose its should not be, normally original body are joint by like rivet spot weld and will be seal with silicon sealant.
Look at the front panel at the radiator, absorber housing front and rear, any chassis pillar, door setup, under body floor for any structure problem...