The changes I made when trying to provide Migration from within Manga Info page.

MangaInfoControler.kt

import eu.kanade.tachiyomi.ui.migration.MigrationController 
import eu.kanade.tachiyomi.ui.migration.SearchController 

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        when (item.itemId) {
            R.id.action_open_in_browser -> openInBrowser()
            R.id.action_open_in_web_view -> openInWebView()
            R.id.action_share -> shareManga()
            R.id.action_add_to_home_screen -> addToHomeScreen()
            R.id.action_migrate -> migrate()
            else -> return super.onOptionsItemSelected(item)
        }
        return true
    }

    /**
     * Migrate the current manga to a different source
     */
    private fun migrate() {
        val migrationController = MigrationController()
        val controller = SearchController(presenter.manga)
        controller.targetController = migrationController

        router.pushController(controller.withFadeTransaction())
    }